2239 lines
74 KiB
C++
2239 lines
74 KiB
C++
/*
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* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2011 Daniel Marjamäki and Cppcheck team.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//---------------------------------------------------------------------------
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// Buffer overrun..
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//---------------------------------------------------------------------------
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#include "checkbufferoverrun.h"
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#include "tokenize.h"
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#include "errorlogger.h"
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#include "mathlib.h"
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#include "symboldatabase.h"
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#include <algorithm>
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#include <sstream>
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#include <list>
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#include <cstring>
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#include <cctype>
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#include <climits>
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#include <cassert> // <- assert
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#include <cstdlib> // <- strtoul
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//---------------------------------------------------------------------------
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// Register this check class (by creating a static instance of it)
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namespace
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{
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CheckBufferOverrun instance;
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}
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//---------------------------------------------------------------------------
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void CheckBufferOverrun::arrayIndexOutOfBounds(const Token *tok, MathLib::bigint size, MathLib::bigint index)
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{
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if (size >= 1)
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{
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std::ostringstream errmsg;
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errmsg << "Array '";
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if (tok)
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errmsg << tok->str();
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else
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errmsg << "array";
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errmsg << "[" << size << "]' index " << index << " out of bounds";
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reportError(tok, Severity::error, "arrayIndexOutOfBounds", errmsg.str().c_str());
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}
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}
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void CheckBufferOverrun::arrayIndexOutOfBounds(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index)
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{
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std::ostringstream oss;
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oss << "Array '" << arrayInfo.varname();
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for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
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oss << "[" << arrayInfo.num(i) << "]";
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oss << "' index ";
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if (index.size() == 1)
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oss << index[0];
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else
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{
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oss << arrayInfo.varname();
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for (unsigned int i = 0; i < index.size(); ++i)
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oss << "[" << index[i] << "]";
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}
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oss << " out of bounds";
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reportError(tok, Severity::error, "arrayIndexOutOfBounds", oss.str().c_str());
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}
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void CheckBufferOverrun::arrayIndexOutOfBounds(const std::list<const Token *> &callstack, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index)
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{
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std::ostringstream oss;
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oss << "Array '" << arrayInfo.varname();
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for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
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oss << "[" << arrayInfo.num(i) << "]";
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oss << "' index ";
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if (index.size() == 1)
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oss << index[0];
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else
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{
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oss << arrayInfo.varname();
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for (unsigned int i = 0; i < index.size(); ++i)
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oss << "[" << index[i] << "]";
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}
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oss << " out of bounds";
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reportError(callstack, Severity::error, "arrayIndexOutOfBounds", oss.str().c_str());
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}
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void CheckBufferOverrun::bufferOverrun(const Token *tok, const std::string &varnames)
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{
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std::string v = varnames;
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while (v.find(" ") != std::string::npos)
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v.erase(v.find(" "), 1);
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std::string errmsg("Buffer access out-of-bounds");
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if (!v.empty())
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errmsg += ": " + v;
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reportError(tok, Severity::error, "bufferAccessOutOfBounds", errmsg);
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}
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void CheckBufferOverrun::strncatUsage(const Token *tok)
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{
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if (_settings && !_settings->isEnabled("style"))
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return;
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reportError(tok, Severity::warning, "strncatUsage",
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"Dangerous usage of strncat - 3rd parameter is the maximum number of characters to append.\n"
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"strncat appends at max its 3rd parameter's amount of characters. The safe way to use "
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"strncat is to calculate remaining space in the buffer and use it as 3rd parameter.");
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}
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void CheckBufferOverrun::outOfBounds(const Token *tok, const std::string &what)
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{
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reportError(tok, Severity::error, "outOfBounds", what + " is out of bounds");
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}
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void CheckBufferOverrun::pointerOutOfBounds(const Token *tok, const std::string &object)
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{
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reportError(tok, Severity::portability, "pointerOutOfBounds", "Undefined behaviour: pointer arithmetic result does not point into or just past the end of the " + object + "\n"
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"Undefined behaviour: Using pointer arithmetic so that the result does not point into or just past the end of the same object. Further information: https://www.securecoding.cert.org/confluence/display/seccode/ARR30-C.+Do+not+form+or+use+out+of+bounds+pointers+or+array+subscripts");
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}
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void CheckBufferOverrun::sizeArgumentAsChar(const Token *tok)
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{
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if (_settings && !_settings->isEnabled("style"))
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return;
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reportError(tok, Severity::warning, "sizeArgumentAsChar", "The size argument is given as a char constant");
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}
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void CheckBufferOverrun::terminateStrncpyError(const Token *tok)
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{
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reportError(tok, Severity::warning, "terminateStrncpy", "After a strncpy() the buffer should be zero-terminated");
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}
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void CheckBufferOverrun::cmdLineArgsError(const Token *tok)
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{
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reportError(tok, Severity::error, "insecureCmdLineArgs", "Buffer overrun possible for long cmd-line args");
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Check array usage..
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//---------------------------------------------------------------------------
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/**
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* @brief This is a helper class to be used with std::find_if
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*/
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class TokenStrEquals
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{
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public:
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/**
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* @param str Token::str() is compared against this.
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*/
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TokenStrEquals(const std::string &str)
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: value(str)
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{
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}
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/**
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* Called automatically by std::find_if
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* @param tok Token inside the list
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*/
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bool operator()(const Token *tok) const
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{
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return value == tok->str();
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}
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private:
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TokenStrEquals& operator=(const TokenStrEquals&); // disallow assignments
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const std::string value;
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};
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/**
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* bailout if variable is used inside if/else/switch block or if there is "break"
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* @param tok token for "if" or "switch"
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* @param varid variable id
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* @return is bailout recommended?
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*/
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static bool bailoutIfSwitch(const Token *tok, const unsigned int varid)
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{
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// Used later to check if the body belongs to a "if"
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const std::string str1(tok->str());
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// Count { and }
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unsigned int indentlevel = 0;
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for (; tok; tok = tok->next())
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{
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if (tok->str() == "{")
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indentlevel++;
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else if (tok->str() == "}")
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{
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// scan the else-block
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if (indentlevel == 1 && Token::simpleMatch(tok, "} else {"))
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{
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--indentlevel;
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continue;
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}
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else if (indentlevel <= 1)
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{
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break;
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}
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--indentlevel;
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}
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// If scanning a "if" block then bailout for "break"
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else if (str1 == "if" && tok->str() == "break")
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return true;
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// bailout for "return"
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else if (tok->str() == "return")
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return true;
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// bailout if varid is found
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else if (tok->varId() == varid)
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return true;
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}
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// No bailout stuff found => return false
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return false;
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}
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/**
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* Parse for loop initialization statement. Look for a counter variable
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* \param tok [in] first token inside the parentheses
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* \param varid [out] varid of counter variable
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* \param init_value [out] init value of counter variable
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* \return success => pointer to the for loop condition. fail => 0
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*/
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static const Token *for_init(const Token *tok, unsigned int &varid, std::string &init_value)
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{
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if (Token::Match(tok, "%var% = %any% ;"))
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{
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if (tok->tokAt(2)->isNumber())
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{
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init_value = tok->strAt(2);
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}
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varid = tok->varId();
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tok = tok->tokAt(4);
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}
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else if (Token::Match(tok, "%type% %var% = %any% ;"))
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{
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if (tok->tokAt(3)->isNumber())
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{
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init_value = tok->strAt(3);
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}
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varid = tok->next()->varId();
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tok = tok->tokAt(5);
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}
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else if (Token::Match(tok, "%type% %type% %var% = %any% ;"))
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{
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if (tok->tokAt(4)->isNumber())
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{
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init_value = tok->strAt(4);
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}
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varid = tok->tokAt(2)->varId();
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tok = tok->tokAt(6);
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}
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else
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return 0;
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return tok;
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}
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/** Parse for condition */
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static bool for_condition(const Token * const tok2, unsigned int varid, std::string &min_value, std::string &max_value, std::string &strindex, bool &maxMinFlipped)
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{
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if (Token::Match(tok2, "%varid% < %num% ;", varid) ||
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Token::Match(tok2, "%varid% != %num% ; ++ %varid%", varid) ||
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Token::Match(tok2, "%varid% != %num% ; %varid% ++", varid))
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{
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maxMinFlipped = false;
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const MathLib::bigint value = MathLib::toLongNumber(tok2->strAt(2));
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max_value = MathLib::toString<MathLib::bigint>(value - 1);
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}
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else if (Token::Match(tok2, "%varid% <= %num% ;", varid))
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{
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maxMinFlipped = false;
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max_value = tok2->strAt(2);
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}
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else if (Token::Match(tok2, "%num% < %varid% ;", varid) ||
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Token::Match(tok2, "%num% != %varid% ; ++ %varid%", varid) ||
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Token::Match(tok2, "%num% != %varid% ; %varid% ++", varid))
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{
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maxMinFlipped = true;
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const MathLib::bigint value = MathLib::toLongNumber(tok2->str());
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max_value = min_value;
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min_value = MathLib::toString<MathLib::bigint>(value + 1);
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}
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else if (Token::Match(tok2, "%num% <= %varid% ;", varid))
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{
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maxMinFlipped = true;
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max_value = min_value;
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min_value = tok2->str();
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}
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else
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{
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return false;
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}
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strindex = tok2->isName() ? tok2->str() : tok2->strAt(2);
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return true;
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}
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/**
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* calculate maximum value of loop variable
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* @param stepvalue token that contains the step value
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* @param min_value the minimum value of loop variable
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* @param max_value maximum value of the loop variable
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*/
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static bool for_maxvalue(const Token * const stepvalue, const std::string &min_value, std::string &max_value)
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{
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if (!MathLib::isInt(stepvalue->str()))
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return false;
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// We have for example code: "for(i=2;i<22;i+=6)
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// We can calculate that max value for i is 20, not 21
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// 21-2 = 19
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// 19/6 = 3
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// 6*3+2 = 20
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const MathLib::bigint num = MathLib::toLongNumber(stepvalue->str());
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MathLib::bigint max = MathLib::toLongNumber(max_value);
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const MathLib::bigint min = MathLib::toLongNumber(min_value);
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max = ((max - min) / num) * num + min;
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max_value = MathLib::toString<MathLib::bigint>(max);
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return true;
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}
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/**
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* Parse the third sub-statement in for head
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* \param tok first token
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* \param varid variable id of counter
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* \param min_value min value of counter
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* \param max_value max value of counter
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* \param maxMinFlipped counting from max to min
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*/
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static bool for3(const Token * const tok,
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unsigned int varid,
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std::string &min_value,
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std::string &max_value,
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const bool maxMinFlipped)
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{
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assert(tok != 0);
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if (Token::Match(tok, "%varid% += %num% )", varid) ||
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Token::Match(tok, "%varid% = %num% + %varid% )", varid))
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{
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if (!for_maxvalue(tok->tokAt(2), min_value, max_value))
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return false;
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}
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else if (Token::Match(tok, "%varid% = %varid% + %num% )", varid))
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{
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if (!for_maxvalue(tok->tokAt(4), min_value, max_value))
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return false;
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}
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else if (Token::Match(tok, "%varid% -= %num% )", varid) ||
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Token::Match(tok, "%varid% = %num% - %varid% )", varid))
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{
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if (!for_maxvalue(tok->tokAt(2), min_value, max_value))
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return false;
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}
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else if (Token::Match(tok, "%varid% = %varid% - %num% )", varid))
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{
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if (!for_maxvalue(tok->tokAt(4), min_value, max_value))
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return false;
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}
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else if (Token::Match(tok, "--| %varid% --| )", varid))
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{
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if (!maxMinFlipped && MathLib::toLongNumber(min_value) < MathLib::toLongNumber(max_value))
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{
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// Code relies on the fact that integer will overflow:
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// for (unsigned int i = 3; i < 5; --i)
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// Set min value in this case to zero.
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max_value = min_value;
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min_value = "0";
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}
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}
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else if (! Token::Match(tok, "++| %varid% ++| )", varid))
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{
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return false;
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}
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return true;
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}
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/**
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* Check is the counter variable increased elsewhere inside the loop or used
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* for anything else except reading
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* \param tok1 first token of for-body
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* \param varid counter variable id
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* \return bailout needed => true
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*/
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static bool for_bailout(const Token * const tok1, unsigned int varid)
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{
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for (const Token *loopTok = tok1; loopTok && loopTok != tok1->link(); loopTok = loopTok->next())
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{
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if (loopTok->varId() == varid)
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{
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// Counter variable used inside loop
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if (Token::Match(loopTok->next(), "+=|-=|++|--|=") ||
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Token::Match(loopTok->previous(), "++|--"))
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{
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return true;
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}
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}
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}
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return false;
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}
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void CheckBufferOverrun::parse_for_body(const Token *tok2, const ArrayInfo &arrayInfo, const std::string &strindex, bool condition_out_of_bounds, unsigned int counter_varid, const std::string &min_counter_value, const std::string &max_counter_value)
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{
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const std::string pattern((arrayInfo.varid() ? std::string("%varid%") : arrayInfo.varname()) + " [ " + strindex + " ]");
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// count { and } for tok2
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int indentlevel2 = 0;
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for (; tok2; tok2 = tok2->next())
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{
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if (tok2->str() == ";" && indentlevel2 == 0)
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break;
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if (tok2->str() == "{")
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++indentlevel2;
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if (tok2->str() == "}")
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{
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--indentlevel2;
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if (indentlevel2 <= 0)
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break;
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}
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// TODO: try to reduce false negatives. This is just a quick fix
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// for TestBufferOverrun::array_index_for_question
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if (tok2->str() == "?")
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break;
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if (Token::simpleMatch(tok2, "for (") && Token::simpleMatch(tok2->next()->link(), ") {"))
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{
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const Token *endpar = tok2->next()->link();
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const Token *startbody = endpar->next();
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const Token *endbody = startbody->link();
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tok2 = endbody;
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continue;
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}
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if (Token::Match(tok2, "if|switch"))
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{
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if (bailoutIfSwitch(tok2, arrayInfo.varid()))
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break;
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}
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if (condition_out_of_bounds && Token::Match(tok2, pattern.c_str(), arrayInfo.varid()))
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{
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bufferOverrun(tok2, arrayInfo.varname());
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break;
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}
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else if (arrayInfo.varid() && counter_varid > 0 && !min_counter_value.empty() && !max_counter_value.empty())
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{
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// Is the loop variable used to calculate the array index?
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// In this scope it is determined if such calculated
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// array indexes are out of bounds.
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// Only the minimum and maximum results of the calculation is
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// determined
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// Minimum calculated array index
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int min_index = 0;
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// Maximum calculated array index
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int max_index = 0;
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if (Token::Match(tok2, "%varid% [ %var% +|-|*|/ %num% ]", arrayInfo.varid()) &&
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tok2->tokAt(2)->varId() == counter_varid)
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{
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// operator: +-*/
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const char action = tok2->strAt(3)[0];
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// second operator
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const std::string &second(tok2->tokAt(4)->str());
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//printf("min_index: %s %c %s\n", min_counter_value.c_str(), action, second.c_str());
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//printf("max_index: %s %c %s\n", max_counter_value.c_str(), action, second.c_str());
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min_index = std::atoi(MathLib::calculate(min_counter_value, second, action, _tokenizer).c_str());
|
|
max_index = std::atoi(MathLib::calculate(max_counter_value, second, action, _tokenizer).c_str());
|
|
}
|
|
else if (Token::Match(tok2, "%varid% [ %num% +|-|*|/ %var% ]", arrayInfo.varid()) &&
|
|
tok2->tokAt(4)->varId() == counter_varid)
|
|
{
|
|
// operator: +-*/
|
|
const char action = tok2->strAt(3)[0];
|
|
|
|
// first operand
|
|
const std::string &first(tok2->tokAt(2)->str());
|
|
|
|
//printf("min_index: %s %c %s\n", first.c_str(), action, min_counter_value.c_str());
|
|
//printf("max_index: %s %c %s\n", first.c_str(), action, max_counter_value.c_str());
|
|
|
|
min_index = std::atoi(MathLib::calculate(first, min_counter_value, action, _tokenizer).c_str());
|
|
max_index = std::atoi(MathLib::calculate(first, max_counter_value, action, _tokenizer).c_str());
|
|
}
|
|
|
|
//printf("min_index = %d, max_index = %d, size = %d\n", min_index, max_index, size);
|
|
if (min_index < 0 || max_index < 0)
|
|
{
|
|
arrayIndexOutOfBounds(tok2, (int)arrayInfo.num(0), std::min(min_index, max_index));
|
|
}
|
|
if (min_index >= (int)arrayInfo.num(0) || max_index >= (int)arrayInfo.num(0))
|
|
{
|
|
arrayIndexOutOfBounds(tok2, (int)arrayInfo.num(0), std::max(min_index, max_index));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
void CheckBufferOverrun::checkFunctionParameter(const Token &tok, unsigned int par, const ArrayInfo &arrayInfo)
|
|
{
|
|
// total_size : which parameter in function call takes the total size?
|
|
std::map<std::string, unsigned int> total_size;
|
|
|
|
total_size["fgets"] = 2; // The second argument for fgets can't exceed the total size of the array
|
|
total_size["memcmp"] = 3;
|
|
total_size["memcpy"] = 3;
|
|
total_size["memmove"] = 3;
|
|
|
|
if (par == 1)
|
|
{
|
|
// reading from array
|
|
// if it is zero terminated properly there won't be buffer overruns
|
|
total_size["strncat"] = 3;
|
|
total_size["strncpy"] = 3;
|
|
total_size["memset"] = 3;
|
|
total_size["fread"] = 1001; // parameter 2 * parameter 3
|
|
total_size["fwrite"] = 1001; // parameter 2 * parameter 3
|
|
}
|
|
|
|
if (par == 2)
|
|
{
|
|
total_size["read"] = 3;
|
|
total_size["pread"] = 3;
|
|
total_size["write"] = 3;
|
|
total_size["recv"] = 3;
|
|
total_size["recvfrom"] = 3;
|
|
total_size["send"] = 3;
|
|
total_size["sendto"] = 3;
|
|
}
|
|
|
|
std::map<std::string, unsigned int>::const_iterator it = total_size.find(tok.str());
|
|
if (it != total_size.end())
|
|
{
|
|
if (arrayInfo.element_size() == 0)
|
|
return;
|
|
|
|
// arg : the index of the "wanted" argument in the function call.
|
|
unsigned int arg = it->second;
|
|
|
|
// Parse function call. When a ',' is seen, arg is decremented.
|
|
// if arg becomes 1 then the current function parameter is the wanted parameter.
|
|
// if arg becomes 1000 then multiply current and next argument.
|
|
for (const Token *tok2 = tok.tokAt(2); tok2; tok2 = tok2->next())
|
|
{
|
|
if (tok2->str() == "(")
|
|
{
|
|
tok2 = tok2->link();
|
|
continue;
|
|
}
|
|
if (tok2->str() == ")")
|
|
break;
|
|
if (tok2->str() == ",")
|
|
{
|
|
--arg;
|
|
if (arg == 1)
|
|
{
|
|
if (Token::Match(tok2, ", %num% ,|)"))
|
|
{
|
|
const MathLib::bigint sz = MathLib::toLongNumber(tok2->strAt(1));
|
|
MathLib::bigint elements = 1;
|
|
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
|
|
elements *= arrayInfo.num(i);
|
|
if (sz < 0 || sz > int(elements * arrayInfo.element_size()))
|
|
{
|
|
bufferOverrun(&tok, arrayInfo.varname());
|
|
}
|
|
}
|
|
|
|
else if (Token::Match(tok2, ", %any% ,|)") && tok2->next()->str()[0] == '\'')
|
|
{
|
|
sizeArgumentAsChar(tok2->next());
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
if (arg == 1000) // special code. This parameter multiplied with the next must not exceed total_size
|
|
{
|
|
if (Token::Match(tok2, ", %num% , %num% ,|)"))
|
|
{
|
|
const MathLib::bigint sz = MathLib::toLongNumber(MathLib::multiply(tok2->strAt(1), tok2->strAt(3)));
|
|
MathLib::bigint elements = 1;
|
|
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
|
|
elements *= arrayInfo.num(i);
|
|
if (sz < 0 || sz > int(elements * arrayInfo.element_size()))
|
|
{
|
|
bufferOverrun(&tok, arrayInfo.varname());
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Calling a user function?
|
|
// only 1-dimensional arrays can be checked currently
|
|
else if (arrayInfo.num().size() == 1)
|
|
{
|
|
const Token *ftok = _tokenizer->getFunctionTokenByName(tok.str().c_str());
|
|
if (Token::Match(ftok, "%var% (") && Token::Match(ftok->next()->link(), ") const| {"))
|
|
{
|
|
// Get varid for the corresponding parameter..
|
|
unsigned int parameter = 1;
|
|
unsigned int parameterVarId = 0;
|
|
for (const Token *ftok2 = ftok->tokAt(2); ftok2; ftok2 = ftok2->next())
|
|
{
|
|
if (ftok2->str() == ",")
|
|
{
|
|
if (parameter >= par)
|
|
break;
|
|
++parameter;
|
|
}
|
|
else if (ftok2->str() == ")")
|
|
break;
|
|
else if (parameter == par && Token::Match(ftok2, "%var% ,|)|["))
|
|
{
|
|
// check type..
|
|
const Token *type = ftok2->previous();
|
|
while (Token::Match(type, "*|const"))
|
|
type = type->previous();
|
|
if (type && _tokenizer->sizeOfType(type) == arrayInfo.element_size())
|
|
parameterVarId = ftok2->varId();
|
|
}
|
|
}
|
|
|
|
// No parameterVarId => bail out
|
|
if (parameterVarId == 0)
|
|
return;
|
|
|
|
// Step into the function scope..
|
|
ftok = ftok->next()->link();
|
|
if (!Token::Match(ftok, ") const| {"))
|
|
return;
|
|
ftok = Token::findmatch(ftok, "{");
|
|
ftok = ftok->next();
|
|
|
|
// Check the parameter usage in the function scope..
|
|
for (; ftok; ftok = ftok->next())
|
|
{
|
|
if (Token::Match(ftok, "if|for|while ("))
|
|
{
|
|
// bailout if there is buffer usage..
|
|
if (bailoutIfSwitch(ftok, parameterVarId))
|
|
{
|
|
break;
|
|
}
|
|
|
|
// no bailout is needed. skip the if-block
|
|
else
|
|
{
|
|
// goto end of if block..
|
|
ftok = ftok->next()->link()->next()->link();
|
|
if (Token::simpleMatch(ftok, "} else {"))
|
|
ftok = ftok->tokAt(2)->link();
|
|
continue;
|
|
}
|
|
}
|
|
|
|
if (ftok->str() == "}")
|
|
break;
|
|
|
|
if (ftok->varId() == parameterVarId)
|
|
{
|
|
if (Token::Match(ftok->previous(), "-- %var%") ||
|
|
Token::Match(ftok, "%var% --"))
|
|
break;
|
|
|
|
if (Token::Match(ftok->previous(), "=|;|{|}|%op% %var% [ %num% ]"))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(ftok->strAt(2));
|
|
if (index >= 0 && arrayInfo.num(0) > 0 && index >= arrayInfo.num(0))
|
|
{
|
|
std::list<const Token *> callstack;
|
|
callstack.push_back(&tok);
|
|
callstack.push_back(ftok);
|
|
|
|
std::vector<MathLib::bigint> indexes;
|
|
indexes.push_back(index);
|
|
|
|
arrayIndexOutOfBounds(callstack, arrayInfo, indexes);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void CheckBufferOverrun::checkFunctionCall(const Token *tok, const ArrayInfo &arrayInfo)
|
|
{
|
|
|
|
// 1st parameter..
|
|
if (Token::Match(tok->tokAt(2), "%varid% ,|)", arrayInfo.varid()))
|
|
checkFunctionParameter(*tok, 1, arrayInfo);
|
|
else if (Token::Match(tok->tokAt(2), "%varid% + %num% ,|)", arrayInfo.varid()))
|
|
{
|
|
const ArrayInfo ai(arrayInfo.limit(MathLib::toLongNumber(tok->strAt(4))));
|
|
checkFunctionParameter(*tok, 1, ai);
|
|
}
|
|
|
|
// goto 2nd parameter and check it..
|
|
for (const Token *tok2 = tok->tokAt(2); tok2; tok2 = tok2->next())
|
|
{
|
|
if (tok2->str() == "(")
|
|
{
|
|
tok2 = tok2->link();
|
|
continue;
|
|
}
|
|
if (tok2->str() == ";" || tok2->str() == ")")
|
|
break;
|
|
if (tok2->str() == ",")
|
|
{
|
|
if (Token::Match(tok2, ", %varid% ,|)", arrayInfo.varid()))
|
|
checkFunctionParameter(*tok, 2, arrayInfo);
|
|
else if (Token::Match(tok2, ", %varid% + %num% ,|)", arrayInfo.varid()))
|
|
{
|
|
const ArrayInfo ai(arrayInfo.limit(MathLib::toLongNumber(tok2->strAt(3))));
|
|
checkFunctionParameter(*tok, 2, ai);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void CheckBufferOverrun::checkScopeForBody(const Token *tok, const ArrayInfo &arrayInfo, bool &bailout)
|
|
{
|
|
bailout = false;
|
|
const Token *tok2 = tok->tokAt(2);
|
|
const MathLib::bigint size = arrayInfo.num(0);
|
|
|
|
// Check if there is a break in the body..
|
|
{
|
|
const Token *bodyStart = tok->next()->link()->next();
|
|
const Token *bodyEnd = bodyStart->link();
|
|
if (Token::findmatch(bodyStart, "break ;", bodyEnd))
|
|
return;
|
|
}
|
|
|
|
unsigned int counter_varid = 0;
|
|
std::string min_counter_value;
|
|
std::string max_counter_value;
|
|
|
|
tok2 = for_init(tok2, counter_varid, min_counter_value);
|
|
if (tok2 == 0 || counter_varid == 0)
|
|
return;
|
|
|
|
bool maxMinFlipped = false;
|
|
std::string strindex;
|
|
if (!for_condition(tok2, counter_varid, min_counter_value, max_counter_value, strindex, maxMinFlipped))
|
|
return;
|
|
|
|
// Get index variable and stopsize.
|
|
bool condition_out_of_bounds = bool(size > 0);
|
|
if (MathLib::toLongNumber(max_counter_value) < size)
|
|
condition_out_of_bounds = false;
|
|
|
|
if (!for3(tok2->tokAt(4), counter_varid, min_counter_value, max_counter_value, maxMinFlipped))
|
|
return;
|
|
|
|
if (Token::Match(tok2->tokAt(4), "%var% =|+=|-=") && MathLib::toLongNumber(max_counter_value) <= size)
|
|
condition_out_of_bounds = false;
|
|
|
|
// Goto the end parenthesis of the for-statement: "for (x; y; z)" ..
|
|
tok2 = tok->next()->link();
|
|
if (!tok2 || !tok2->tokAt(5))
|
|
{
|
|
bailout = true;
|
|
return;
|
|
}
|
|
|
|
// Check is the counter variable increased elsewhere inside the loop or used
|
|
// for anything else except reading
|
|
if (for_bailout(tok2->next(), counter_varid))
|
|
{
|
|
bailout = true;
|
|
return;
|
|
}
|
|
|
|
parse_for_body(tok2->next(), arrayInfo, strindex, condition_out_of_bounds, counter_varid, min_counter_value, max_counter_value);
|
|
}
|
|
|
|
|
|
void CheckBufferOverrun::checkScope(const Token *tok, const std::vector<std::string> &varname, const MathLib::bigint size, const MathLib::bigint total_size, unsigned int varid)
|
|
{
|
|
std::string varnames;
|
|
for (unsigned int i = 0; i < varname.size(); ++i)
|
|
varnames += (i == 0 ? "" : " . ") + varname[i];
|
|
|
|
const unsigned char varc(static_cast<unsigned char>(varname.empty() ? 0U : (varname.size() - 1) * 2U));
|
|
|
|
if (Token::simpleMatch(tok, "return"))
|
|
{
|
|
tok = tok->next();
|
|
if (!tok)
|
|
return;
|
|
}
|
|
|
|
// Array index..
|
|
if (varid > 0)
|
|
{
|
|
if (Token::Match(tok, "%varid% [ %num% ]", varid))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(2));
|
|
if (index >= size)
|
|
{
|
|
arrayIndexOutOfBounds(tok, size, index);
|
|
}
|
|
}
|
|
}
|
|
else if (Token::Match(tok, (varnames + " [ %num% ]").c_str()))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(2 + varc));
|
|
if (index >= size)
|
|
{
|
|
arrayIndexOutOfBounds(tok->tokAt(varc), size, index);
|
|
}
|
|
}
|
|
|
|
// If the result of pointer arithmetic means that the pointer is
|
|
// out of bounds then this flag will be set.
|
|
bool pointerIsOutOfBounds = false;
|
|
|
|
// Count { and } for tok
|
|
int indentlevel = 0;
|
|
for (; tok; tok = tok->next())
|
|
{
|
|
if (tok->str() == "{")
|
|
{
|
|
++indentlevel;
|
|
}
|
|
|
|
else if (tok->str() == "}")
|
|
{
|
|
--indentlevel;
|
|
if (indentlevel < 0)
|
|
return;
|
|
}
|
|
|
|
if (varid != 0 && Token::Match(tok, "%varid% = new|malloc|realloc", varid))
|
|
{
|
|
// Abort
|
|
break;
|
|
}
|
|
|
|
// reassign buffer => bailout
|
|
if (varid > 0 &&
|
|
Token::Match(tok, "[;{}] %varid% =", varid) &&
|
|
!Token::Match(tok->tokAt(3), "%varid%", varid))
|
|
break;
|
|
|
|
// Array index..
|
|
if (varid > 0)
|
|
{
|
|
if (!tok->isName() && !Token::Match(tok, "[.&]") && Token::Match(tok->next(), "%varid% [ %num% ]", varid))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(3));
|
|
if (index < 0 || index >= size)
|
|
{
|
|
if (index > size || !Token::simpleMatch(tok->previous(), "& ("))
|
|
{
|
|
arrayIndexOutOfBounds(tok->next(), size, index);
|
|
}
|
|
}
|
|
}
|
|
if (Token::Match(tok, "return %varid% [ %num% ]", varid))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(3));
|
|
if (index < 0 || index >= size)
|
|
{
|
|
arrayIndexOutOfBounds(tok->next(), size, index);
|
|
}
|
|
}
|
|
}
|
|
else if (!tok->isName() && !Token::Match(tok, "[.&]") && Token::Match(tok->next(), (varnames + " [ %num% ]").c_str()))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(3 + varc));
|
|
if (index >= size)
|
|
{
|
|
arrayIndexOutOfBounds(tok->tokAt(1 + varc), size, index);
|
|
}
|
|
tok = tok->tokAt(4);
|
|
continue;
|
|
}
|
|
|
|
|
|
// memset, memcmp, memcpy, strncpy, fgets..
|
|
if (varid == 0 && size > 0)
|
|
{
|
|
ArrayInfo arrayInfo(0U,
|
|
varnames,
|
|
(unsigned int)(total_size / size),
|
|
(unsigned int)size);
|
|
if (Token::Match(tok, ("%var% ( " + varnames + " ,").c_str()))
|
|
checkFunctionParameter(*tok, 1, arrayInfo);
|
|
if (Token::Match(tok, ("%var% ( %var% , " + varnames + " ,").c_str()))
|
|
checkFunctionParameter(*tok, 2, arrayInfo);
|
|
}
|
|
|
|
// Loop..
|
|
if (Token::simpleMatch(tok, "for ("))
|
|
{
|
|
const ArrayInfo arrayInfo(varid, varnames, (unsigned int)size, (unsigned int)total_size);
|
|
bool bailout = false;
|
|
checkScopeForBody(tok, arrayInfo, bailout);
|
|
if (bailout)
|
|
break;
|
|
continue;
|
|
}
|
|
|
|
// Writing data into array..
|
|
if ((varid > 0 && Token::Match(tok, "strcpy|strcat ( %varid% , %str% )", varid)) ||
|
|
(varid == 0 && Token::Match(tok, ("strcpy|strcat ( " + varnames + " , %str% )").c_str())))
|
|
{
|
|
const std::size_t len = Token::getStrLength(tok->tokAt(varc + 4));
|
|
if (total_size > 0 && len >= (unsigned int)total_size)
|
|
{
|
|
bufferOverrun(tok, varid > 0 ? "" : varnames.c_str());
|
|
continue;
|
|
}
|
|
}
|
|
|
|
|
|
// Detect few strcat() calls
|
|
const std::string strcatPattern = varid > 0 ? std::string("strcat ( %varid% , %str% ) ;") : ("strcat ( " + varnames + " , %str% ) ;");
|
|
if (Token::Match(tok, strcatPattern.c_str(), varid))
|
|
{
|
|
size_t charactersAppend = 0;
|
|
const Token *tok2 = tok;
|
|
|
|
while (tok2 && Token::Match(tok2, strcatPattern.c_str(), varid))
|
|
{
|
|
charactersAppend += Token::getStrLength(tok2->tokAt(4 + varc));
|
|
if (charactersAppend >= static_cast<size_t>(total_size))
|
|
{
|
|
bufferOverrun(tok2);
|
|
break;
|
|
}
|
|
tok2 = tok2->tokAt(7 + varc);
|
|
}
|
|
}
|
|
|
|
// sprintf..
|
|
// TODO: change total_size to an unsigned value and remove the "&& total_size > 0" check.
|
|
const std::string sprintfPattern = varid > 0 ? std::string("sprintf ( %varid% , %str% [,)]") : ("sprintf ( " + varnames + " , %str% [,)]");
|
|
if (Token::Match(tok, sprintfPattern.c_str(), varid) && total_size > 0)
|
|
{
|
|
checkSprintfCall(tok, static_cast<unsigned int>(total_size));
|
|
}
|
|
|
|
// snprintf..
|
|
const std::string snprintfPattern = varid > 0 ? std::string("snprintf ( %varid% , %num% ,") : ("snprintf ( " + varnames + " , %num% ,");
|
|
if (Token::Match(tok, snprintfPattern.c_str(), varid))
|
|
{
|
|
const MathLib::bigint n = MathLib::toLongNumber(tok->strAt(4 + varc));
|
|
if (n > total_size)
|
|
outOfBounds(tok->tokAt(4 + varc), "snprintf size");
|
|
}
|
|
|
|
// Check function call..
|
|
if (Token::Match(tok, "%var% (") && total_size > 0)
|
|
{
|
|
// No varid => function calls are not handled
|
|
if (varid == 0)
|
|
continue;
|
|
|
|
const ArrayInfo arrayInfo(varid, varnames, size, total_size / size);
|
|
checkFunctionCall(tok, arrayInfo);
|
|
}
|
|
|
|
// undefined behaviour: result of pointer arithmetic is out of bounds
|
|
if (varid && Token::Match(tok, "= %varid% + %num% ;", varid))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(3));
|
|
if (index > size && _settings->isEnabled("style"))
|
|
pointerOutOfBounds(tok->next(), "buffer");
|
|
if (index >= size && Token::Match(tok->tokAt(-2), "[;{}] %varid% =", varid))
|
|
pointerIsOutOfBounds = true;
|
|
}
|
|
|
|
if (pointerIsOutOfBounds && Token::Match(tok, "[;{}=] * %varid% [;=]", varid))
|
|
{
|
|
outOfBounds(tok->tokAt(2), tok->strAt(2));
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo)
|
|
{
|
|
const MathLib::bigint total_size = arrayInfo.num(0) * arrayInfo.element_size();
|
|
|
|
// Count { and } for tok
|
|
unsigned int indentlevel = 0;
|
|
for (; tok; tok = tok->next())
|
|
{
|
|
if (tok->str() == "{")
|
|
{
|
|
++indentlevel;
|
|
}
|
|
|
|
else if (tok->str() == "}")
|
|
{
|
|
if (indentlevel == 0)
|
|
return;
|
|
--indentlevel;
|
|
}
|
|
|
|
// Skip array declarations
|
|
else if (Token::Match(tok, "[;{}] %type% *| %var% [") &&
|
|
tok->strAt(1) != "return")
|
|
{
|
|
tok = tok->tokAt(3);
|
|
continue;
|
|
}
|
|
|
|
else if (Token::Match(tok, "%varid% [ %num% ]", arrayInfo.varid()))
|
|
{
|
|
std::vector<MathLib::bigint> indexes;
|
|
for (const Token *tok2 = tok->next(); Token::Match(tok2, "[ %num% ]"); tok2 = tok2->tokAt(3))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok2->strAt(1));
|
|
if (index < 0)
|
|
{
|
|
indexes.clear();
|
|
break;
|
|
}
|
|
indexes.push_back(index);
|
|
}
|
|
if (indexes.size() == arrayInfo.num().size())
|
|
{
|
|
// Check if the indexes point outside the whole array..
|
|
// char a[10][10];
|
|
// a[0][20] <-- ok.
|
|
// a[9][20] <-- error.
|
|
|
|
// total number of elements of array..
|
|
MathLib::bigint totalElements = 1;
|
|
|
|
// total index..
|
|
MathLib::bigint totalIndex = 0;
|
|
|
|
// calculate the totalElements and totalIndex..
|
|
for (unsigned int i = 0; i < indexes.size(); ++i)
|
|
{
|
|
std::size_t ri = indexes.size() - 1 - i;
|
|
totalIndex += indexes[ri] * totalElements;
|
|
totalElements *= arrayInfo.num(ri);
|
|
}
|
|
|
|
// totalElements == 0 => Unknown size
|
|
if (totalElements == 0)
|
|
continue;
|
|
|
|
// just taking the address?
|
|
const bool addr(Token::Match(tok->previous(), "[.&]") ||
|
|
Token::simpleMatch(tok->tokAt(-2), "& ("));
|
|
|
|
// Is totalIndex in bounds?
|
|
if (totalIndex > totalElements || (!addr && totalIndex == totalElements))
|
|
{
|
|
arrayIndexOutOfBounds(tok, arrayInfo, indexes);
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
// Loop..
|
|
else if (Token::simpleMatch(tok, "for ("))
|
|
{
|
|
bool bailout = false;
|
|
checkScopeForBody(tok, arrayInfo, bailout);
|
|
if (bailout)
|
|
break;
|
|
continue;
|
|
}
|
|
|
|
|
|
// Check function call..
|
|
if (Token::Match(tok, "%var% ("))
|
|
{
|
|
checkFunctionCall(tok, arrayInfo);
|
|
}
|
|
|
|
if (_settings->isEnabled("style"))
|
|
{
|
|
// check for strncpy which is not terminated
|
|
if ((Token::Match(tok, "strncpy ( %varid% , %var% , %num% )", arrayInfo.varid())))
|
|
{
|
|
// strncpy takes entire variable length as input size
|
|
if ((unsigned int)MathLib::toLongNumber(tok->strAt(6)) >= total_size)
|
|
{
|
|
const Token *tok2 = tok->next()->link()->next();
|
|
for (; tok2; tok2 = tok2->next())
|
|
{
|
|
if (tok2->varId() == tok->tokAt(2)->varId())
|
|
{
|
|
if (!Token::Match(tok2, "%varid% [ %any% ] = 0 ;", tok->tokAt(2)->varId()))
|
|
{
|
|
// this is currently 'experimental'. See TestBufferOverrun::terminateStrncpy3
|
|
if (_settings->experimental)
|
|
terminateStrncpyError(tok);
|
|
}
|
|
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Dangerous usage of strncat..
|
|
if (Token::Match(tok, "strncpy|strncat ( %varid% , %any% , %num% )", arrayInfo.varid()))
|
|
{
|
|
if (tok->str() == "strncat")
|
|
{
|
|
const MathLib::bigint n = MathLib::toLongNumber(tok->strAt(6));
|
|
if (n >= total_size)
|
|
strncatUsage(tok);
|
|
}
|
|
|
|
// Dangerous usage of strncpy + strncat..
|
|
if (Token::Match(tok->tokAt(8), "; strncat ( %varid% , %any% , %num% )", arrayInfo.varid()))
|
|
{
|
|
const MathLib::bigint n = MathLib::toLongNumber(tok->strAt(6)) + MathLib::toLongNumber(tok->strAt(15));
|
|
if (n > total_size)
|
|
strncatUsage(tok->tokAt(9));
|
|
}
|
|
}
|
|
|
|
// Writing data into array..
|
|
if (Token::Match(tok, "strcpy|strcat ( %varid% , %str% )", arrayInfo.varid()))
|
|
{
|
|
const std::size_t len = Token::getStrLength(tok->tokAt(4));
|
|
if (total_size > 0 && len >= (unsigned int)total_size)
|
|
{
|
|
bufferOverrun(tok, arrayInfo.varname());
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Detect few strcat() calls
|
|
if (total_size > 0 && Token::Match(tok, "strcat ( %varid% , %str% ) ;", arrayInfo.varid()))
|
|
{
|
|
std::size_t charactersAppend = 0;
|
|
const Token *tok2 = tok;
|
|
|
|
while (tok2 && Token::Match(tok2, "strcat ( %varid% , %str% ) ;", arrayInfo.varid()))
|
|
{
|
|
charactersAppend += Token::getStrLength(tok2->tokAt(4));
|
|
if (charactersAppend >= (unsigned int)total_size)
|
|
{
|
|
bufferOverrun(tok2, arrayInfo.varname());
|
|
break;
|
|
}
|
|
tok2 = tok2->tokAt(7);
|
|
}
|
|
}
|
|
|
|
|
|
if (Token::Match(tok, "sprintf ( %varid% , %str% [,)]", arrayInfo.varid()))
|
|
{
|
|
checkSprintfCall(tok, total_size);
|
|
}
|
|
|
|
// snprintf..
|
|
if (total_size > 0 && Token::Match(tok, "snprintf ( %varid% , %num% ,", arrayInfo.varid()))
|
|
{
|
|
const MathLib::bigint n = MathLib::toLongNumber(tok->strAt(4));
|
|
if (n > total_size)
|
|
outOfBounds(tok->tokAt(4), "snprintf size");
|
|
}
|
|
|
|
// undefined behaviour: result of pointer arithmetic is out of bounds
|
|
if (_settings->isEnabled("style") && Token::Match(tok, "= %varid% + %num% ;", arrayInfo.varid()))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->strAt(3));
|
|
if (index < 0 || index > arrayInfo.num(0))
|
|
{
|
|
pointerOutOfBounds(tok->next(), "array");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Checking local variables in a scope
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckBufferOverrun::checkGlobalAndLocalVariable()
|
|
{
|
|
// check all known fixed size arrays first by just looking them up
|
|
for (size_t i = 1; i <= _tokenizer->varIdCount(); i++)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(i);
|
|
if (var && var->isArray() && var->dimension(0) > 0)
|
|
{
|
|
ArrayInfo arrayInfo(var, _tokenizer);
|
|
const Token *tok = var->nameToken();
|
|
while (tok && tok->str() != ";")
|
|
{
|
|
if (tok->str() == "{")
|
|
{
|
|
if (Token::simpleMatch(tok->previous(), "= {"))
|
|
tok = tok->link();
|
|
else
|
|
break;
|
|
}
|
|
tok = tok->next();
|
|
}
|
|
if (!tok)
|
|
break;
|
|
if (tok->str() == "{")
|
|
tok = tok->next();
|
|
checkScope(tok, arrayInfo);
|
|
}
|
|
}
|
|
|
|
// find all dynamically allocated arrays next by parsing the token stream
|
|
// Count { and } when parsing all tokens
|
|
int indentlevel = 0;
|
|
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
|
|
{
|
|
if (tok->str() == "{")
|
|
++indentlevel;
|
|
|
|
else if (tok->str() == "}")
|
|
--indentlevel;
|
|
|
|
// size : Max array index
|
|
MathLib::bigint size = 0;
|
|
|
|
// type : The type of a array element
|
|
std::string type;
|
|
|
|
// varid : The variable id for the array
|
|
unsigned int varid = 0;
|
|
|
|
// nextTok : number of tokens used in variable declaration - used to skip to next statement.
|
|
int nextTok = 0;
|
|
|
|
// if the previous token exists, it must be either a variable name or "[;{}]"
|
|
if (tok->previous() && (!tok->previous()->isName() && !Token::Match(tok->previous(), "[;{}]")))
|
|
continue;
|
|
|
|
_errorLogger->reportProgress(_tokenizer->getFiles()->front(),
|
|
"Check (BufferOverrun::checkGlobalAndLocalVariable)",
|
|
tok->progressValue());
|
|
|
|
if (indentlevel > 0 && Token::Match(tok, "[*;{}] %var% = new %type% [ %num% ]"))
|
|
{
|
|
size = MathLib::toLongNumber(tok->strAt(6));
|
|
type = tok->strAt(4);
|
|
varid = tok->tokAt(1)->varId();
|
|
nextTok = 8;
|
|
}
|
|
else if (indentlevel > 0 && Token::Match(tok, "[*;{}] %var% = new %type% ( %num% )"))
|
|
{
|
|
size = 1;
|
|
type = tok->strAt(4);
|
|
varid = tok->tokAt(1)->varId();
|
|
nextTok = 8;
|
|
}
|
|
else if (indentlevel > 0 &&
|
|
Token::Match(tok, "[;{}] %var% = %str% ;") &&
|
|
tok->next()->varId() > 0 &&
|
|
NULL != Token::findmatch(_tokenizer->tokens(), "[;{}] const| %type% * %varid% ;", tok->next()->varId()))
|
|
{
|
|
size = 1 + int(tok->tokAt(3)->strValue().size());
|
|
type = "char";
|
|
varid = tok->next()->varId();
|
|
nextTok = 4;
|
|
}
|
|
else if (indentlevel > 0 && Token::Match(tok, "[*;{}] %var% = malloc|alloca ( %num% ) ;"))
|
|
{
|
|
size = MathLib::toLongNumber(tok->strAt(5));
|
|
type = "char"; // minimum type, typesize=1
|
|
varid = tok->tokAt(1)->varId();
|
|
nextTok = 7;
|
|
|
|
if (varid > 0)
|
|
{
|
|
// get type of variable
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(varid);
|
|
/** @todo false negatives: this may be too conservative */
|
|
if (!var || var->typeEndToken()->str() != "*" || var->typeStartToken()->next() != var->typeEndToken())
|
|
continue;
|
|
|
|
// get name of variable
|
|
type = var->typeStartToken()->str();
|
|
|
|
// malloc() gets count of bytes and not count of
|
|
// elements, so we should calculate count of elements
|
|
// manually
|
|
unsigned int sizeOfType = _tokenizer->sizeOfType(var->typeStartToken());
|
|
if (sizeOfType > 0)
|
|
size /= static_cast<int>(sizeOfType);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
continue;
|
|
}
|
|
|
|
if (varid == 0)
|
|
continue;
|
|
|
|
Token sizeTok(0);
|
|
sizeTok.str(type);
|
|
const MathLib::bigint total_size = size * static_cast<int>(_tokenizer->sizeOfType(&sizeTok));
|
|
if (total_size == 0)
|
|
continue;
|
|
|
|
std::vector<std::string> v;
|
|
checkScope(tok->tokAt(nextTok), v, size, total_size, varid);
|
|
}
|
|
}
|
|
//---------------------------------------------------------------------------
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Checking member variables of structs..
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckBufferOverrun::checkStructVariable()
|
|
{
|
|
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
|
|
{
|
|
if (tok->str() == "{")
|
|
{
|
|
tok = tok->link();
|
|
}
|
|
|
|
if (!Token::Match(tok, "struct|class %var% {|:"))
|
|
continue;
|
|
|
|
const std::string &structname = tok->next()->str();
|
|
const Token *tok2 = tok;
|
|
|
|
while (tok2 && tok2->str() != "{")
|
|
tok2 = tok2->next();
|
|
|
|
// Found a struct declaration. Search for arrays..
|
|
for (; tok2; tok2 = tok2->next())
|
|
{
|
|
// skip inner scopes..
|
|
if (tok2->next() && tok2->next()->str() == "{")
|
|
{
|
|
tok2 = tok2->next()->link();
|
|
continue;
|
|
}
|
|
|
|
if (tok2->str() == "}")
|
|
break;
|
|
|
|
ArrayInfo arrayInfo;
|
|
if (!arrayInfo.declare(tok2->next(), *_tokenizer))
|
|
continue;
|
|
|
|
// Only handling 1-dimensional arrays yet..
|
|
if (arrayInfo.num().size() > 1)
|
|
continue;
|
|
|
|
// Skip array with only 0/1 elements because those are
|
|
// often overrun intentionally
|
|
if (arrayInfo.num(0) <= 1)
|
|
continue;
|
|
|
|
std::vector<std::string> varname;
|
|
varname.push_back("");
|
|
varname.push_back(arrayInfo.varname());
|
|
|
|
// Class member variable => Check functions
|
|
if (tok->str() == "class")
|
|
{
|
|
std::string func_pattern(structname + " :: %var% (");
|
|
const Token *tok3 = Token::findmatch(_tokenizer->tokens(), func_pattern.c_str());
|
|
while (tok3)
|
|
{
|
|
for (const Token *tok4 = tok3; tok4; tok4 = tok4->next())
|
|
{
|
|
if (Token::Match(tok4, "[;{}]"))
|
|
break;
|
|
|
|
if (Token::simpleMatch(tok4, ") {"))
|
|
{
|
|
std::vector<std::string> v;
|
|
checkScope(tok4->tokAt(2), v, static_cast<int>(arrayInfo.num(0)), static_cast<int>(arrayInfo.num(0) * arrayInfo.element_size()), arrayInfo.varid());
|
|
break;
|
|
}
|
|
}
|
|
tok3 = Token::findmatch(tok3->next(), func_pattern.c_str());
|
|
}
|
|
}
|
|
|
|
for (const Token *tok3 = _tokenizer->tokens(); tok3; tok3 = tok3->next())
|
|
{
|
|
if (tok3->str() != structname)
|
|
continue;
|
|
|
|
// Declare variable: Fred fred1;
|
|
if (Token::Match(tok3->next(), "%var% ;"))
|
|
varname[0] = tok3->strAt(1);
|
|
|
|
// Declare pointer: Fred *fred1
|
|
else if (Token::Match(tok3->next(), "* %var% [,);=]"))
|
|
varname[0] = tok3->strAt(2);
|
|
|
|
else
|
|
continue;
|
|
|
|
// Goto end of statement.
|
|
const Token *CheckTok = NULL;
|
|
while (tok3)
|
|
{
|
|
// End of statement.
|
|
if (tok3->str() == ";")
|
|
{
|
|
CheckTok = tok3;
|
|
break;
|
|
}
|
|
|
|
// End of function declaration..
|
|
if (Token::simpleMatch(tok3, ") ;"))
|
|
break;
|
|
|
|
// Function implementation..
|
|
if (Token::simpleMatch(tok3, ") {"))
|
|
{
|
|
CheckTok = tok3->tokAt(2);
|
|
break;
|
|
}
|
|
|
|
tok3 = tok3->next();
|
|
}
|
|
|
|
if (!tok3)
|
|
break;
|
|
|
|
if (!CheckTok)
|
|
continue;
|
|
|
|
// Check variable usage..
|
|
checkScope(CheckTok, varname, static_cast<int>(arrayInfo.num(0)), static_cast<int>(arrayInfo.num(0) * arrayInfo.element_size()), 0);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckBufferOverrun::bufferOverrun()
|
|
{
|
|
checkGlobalAndLocalVariable();
|
|
checkStructVariable();
|
|
checkBufferAllocatedWithStrlen();
|
|
checkInsecureCmdLineArgs();
|
|
}
|
|
//---------------------------------------------------------------------------
|
|
|
|
|
|
MathLib::bigint CheckBufferOverrun::countSprintfLength(const std::string &input_string, const std::list<const Token*> ¶meters)
|
|
{
|
|
bool percentCharFound = false;
|
|
std::size_t input_string_size = 1;
|
|
bool handleNextParameter = false;
|
|
std::string digits_string = "";
|
|
bool i_d_x_f_found = false;
|
|
std::list<const Token*>::const_iterator paramIter = parameters.begin();
|
|
std::size_t parameterLength = 0;
|
|
for (std::string::size_type i = 0; i < input_string.length(); ++i)
|
|
{
|
|
if (input_string[i] == '\\')
|
|
{
|
|
if (input_string[i+1] == '0')
|
|
break;
|
|
|
|
++input_string_size;
|
|
++i;
|
|
continue;
|
|
}
|
|
|
|
if (percentCharFound)
|
|
{
|
|
switch (input_string[i])
|
|
{
|
|
case 'f':
|
|
case 'x':
|
|
case 'X':
|
|
case 'i':
|
|
i_d_x_f_found = true;
|
|
case 'c':
|
|
case 'e':
|
|
case 'E':
|
|
case 'g':
|
|
case 'o':
|
|
case 'u':
|
|
case 'p':
|
|
case 'n':
|
|
handleNextParameter = true;
|
|
break;
|
|
case 'd':
|
|
i_d_x_f_found = true;
|
|
if (paramIter != parameters.end() && *paramIter && (*paramIter)->str()[0] != '"')
|
|
parameterLength = (*paramIter)->str().length();
|
|
|
|
handleNextParameter = true;
|
|
break;
|
|
case 's':
|
|
if (paramIter != parameters.end() && *paramIter && (*paramIter)->str()[0] == '"')
|
|
parameterLength = Token::getStrLength(*paramIter);
|
|
|
|
handleNextParameter = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (input_string[i] == '%')
|
|
percentCharFound = !percentCharFound;
|
|
else if (percentCharFound)
|
|
{
|
|
digits_string.append(1, input_string[i]);
|
|
}
|
|
|
|
if (!percentCharFound)
|
|
input_string_size++;
|
|
|
|
if (handleNextParameter)
|
|
{
|
|
unsigned int tempDigits = static_cast<unsigned int>(std::abs(std::atoi(digits_string.c_str())));
|
|
if (i_d_x_f_found)
|
|
tempDigits = std::max(static_cast<unsigned int>(tempDigits), 1U);
|
|
|
|
if (digits_string.find('.') != std::string::npos)
|
|
{
|
|
const std::string endStr = digits_string.substr(digits_string.find('.') + 1);
|
|
unsigned int maxLen = std::max(static_cast<unsigned int>(std::abs(std::atoi(endStr.c_str()))), 1U);
|
|
|
|
if (input_string[i] == 's')
|
|
{
|
|
// For strings, the length after the dot "%.2s" will limit
|
|
// the length of the string.
|
|
if (parameterLength > maxLen)
|
|
parameterLength = maxLen;
|
|
}
|
|
else
|
|
{
|
|
// For integers, the length after the dot "%.2d" can
|
|
// increase required length
|
|
if (tempDigits < maxLen)
|
|
tempDigits = maxLen;
|
|
}
|
|
}
|
|
|
|
if (tempDigits < parameterLength)
|
|
input_string_size += parameterLength;
|
|
else
|
|
input_string_size += tempDigits;
|
|
|
|
parameterLength = 0;
|
|
digits_string = "";
|
|
i_d_x_f_found = false;
|
|
percentCharFound = false;
|
|
handleNextParameter = false;
|
|
if (paramIter != parameters.end())
|
|
++paramIter;
|
|
}
|
|
}
|
|
|
|
return (MathLib::bigint)input_string_size;
|
|
}
|
|
|
|
void CheckBufferOverrun::checkSprintfCall(const Token *tok, const MathLib::bigint size)
|
|
{
|
|
if (size == 0)
|
|
return;
|
|
|
|
const Token *end = tok->next()->link();
|
|
|
|
// Count the number of tokens in the buffer variable's name
|
|
int varc = 0;
|
|
for (const Token *tok1 = tok->tokAt(3); tok1 != end; tok1 = tok1->next())
|
|
{
|
|
if (tok1->str() == ",")
|
|
break;
|
|
++ varc;
|
|
}
|
|
|
|
std::list<const Token*> parameters;
|
|
if (tok->tokAt(5 + varc)->str() == ",")
|
|
{
|
|
for (const Token *tok2 = tok->tokAt(5 + varc); tok2 && tok2 != end; tok2 = tok2->next())
|
|
{
|
|
if (Token::Match(tok2, ", %any% [,)]"))
|
|
{
|
|
if (Token::Match(tok2->next(), "%str%"))
|
|
parameters.push_back(tok2->next());
|
|
|
|
else if (Token::Match(tok2->next(), "%num%"))
|
|
parameters.push_back(tok2->next());
|
|
|
|
else
|
|
parameters.push_back(0);
|
|
}
|
|
else
|
|
{
|
|
// Parameter is more complex, than just a value or variable. Ignore it for now
|
|
// and skip to next token.
|
|
parameters.push_back(0);
|
|
|
|
// count parentheses for tok3
|
|
int ind = 0;
|
|
for (const Token *tok3 = tok2->next(); tok3; tok3 = tok3->next())
|
|
{
|
|
if (tok3->str() == "(")
|
|
++ind;
|
|
|
|
else if (tok3->str() == ")")
|
|
{
|
|
--ind;
|
|
if (ind < 0)
|
|
break;
|
|
}
|
|
|
|
else if (ind == 0 && tok3->str() == ",")
|
|
{
|
|
tok2 = tok3->previous();
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (ind < 0)
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
MathLib::bigint len = countSprintfLength(tok->tokAt(4 + varc)->strValue(), parameters);
|
|
if (len > size)
|
|
{
|
|
bufferOverrun(tok);
|
|
}
|
|
}
|
|
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Checking for allocating insufficient memory for copying a string by
|
|
// allocating only strlen(src) bytes instead of strlen(src) + 1 bytes (one
|
|
// extra for the terminating null character).
|
|
// Example:
|
|
// char *b = malloc(strlen(a)); // Should be malloc(strlen(a) + 1);
|
|
// strcpy(b, a); // <== Buffer overrun
|
|
//---------------------------------------------------------------------------
|
|
void CheckBufferOverrun::checkBufferAllocatedWithStrlen()
|
|
{
|
|
const char pattern[] = "%var% = new|malloc|g_malloc|g_try_malloc|realloc|g_realloc|g_try_realloc";
|
|
for (const Token *tok = Token::findmatch(_tokenizer->tokens(), pattern); tok; tok = Token::findmatch(tok->next(),pattern))
|
|
{
|
|
unsigned int dstVarId;
|
|
unsigned int srcVarId;
|
|
|
|
// Look for allocation of a buffer based on the size of a string
|
|
if (Token::Match(tok, "%var% = malloc|g_malloc|g_try_malloc ( strlen ( %var% ) )"))
|
|
{
|
|
dstVarId = tok->varId();
|
|
srcVarId = tok->tokAt(6)->varId();
|
|
tok = tok->tokAt(8);
|
|
}
|
|
else if (Token::Match(tok, "%var% = new char [ strlen ( %var% ) ]"))
|
|
{
|
|
dstVarId = tok->varId();
|
|
srcVarId = tok->tokAt(7)->varId();
|
|
tok = tok->tokAt(9);
|
|
}
|
|
else if (Token::Match(tok, "%var% = realloc|g_realloc|g_try_realloc ( %var% , strlen ( %var% ) )"))
|
|
{
|
|
dstVarId = tok->varId();
|
|
srcVarId = tok->tokAt(8)->varId();
|
|
tok = tok->tokAt(10);
|
|
}
|
|
else
|
|
continue;
|
|
|
|
// count { and } for tok
|
|
int indentlevel = 0;
|
|
for (; tok && tok->next(); tok = tok->next())
|
|
{
|
|
// To avoid false positives and added complexity, we will only look for
|
|
// improper usage of the buffer within the block that it was allocated
|
|
if (tok->str() == "{")
|
|
{
|
|
++indentlevel;
|
|
}
|
|
|
|
else if (tok->str() == "}")
|
|
{
|
|
--indentlevel;
|
|
if (indentlevel < 0)
|
|
return;
|
|
}
|
|
|
|
// If the buffers are modified, we can't be sure of their sizes
|
|
if (tok->varId() == srcVarId || tok->varId() == dstVarId)
|
|
break;
|
|
|
|
if (Token::Match(tok, "strcpy ( %varid% , %var% )", dstVarId) &&
|
|
tok->tokAt(4)->varId() == srcVarId)
|
|
{
|
|
bufferOverrun(tok);
|
|
}
|
|
else if (Token::Match(tok, "sprintf ( %varid% , %str% , %var% )", dstVarId) &&
|
|
tok->tokAt(6)->varId() == srcVarId &&
|
|
tok->tokAt(4)->str().find("%s") != std::string::npos)
|
|
{
|
|
bufferOverrun(tok);
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Checking for buffer overflow caused by copying command line arguments
|
|
// into fixed-sized buffers without checking to make sure that the command
|
|
// line arguments will not overflow the buffer.
|
|
//
|
|
// int main(int argc, char* argv[])
|
|
// {
|
|
// char prog[10];
|
|
// strcpy(prog, argv[0]); <-- Possible buffer overrun
|
|
// }
|
|
//---------------------------------------------------------------------------
|
|
void CheckBufferOverrun::checkInsecureCmdLineArgs()
|
|
{
|
|
const char pattern[] = "main ( int %var% , char *";
|
|
for (const Token *tok = Token::findmatch(_tokenizer->tokens(), pattern); tok; tok = Token::findmatch(tok->next(),pattern))
|
|
{
|
|
// Get the name of the argv variable
|
|
unsigned int varid = 0;
|
|
if (Token::Match(tok, "main ( int %var% , char * %var% [ ] ,|)"))
|
|
{
|
|
varid = tok->tokAt(7)->varId();
|
|
|
|
}
|
|
else if (Token::Match(tok, "main ( int %var% , char * * %var% ,|)"))
|
|
{
|
|
varid = tok->tokAt(8)->varId();
|
|
}
|
|
if (varid == 0)
|
|
continue;
|
|
|
|
// Jump to the opening curly brace
|
|
tok = tok->next()->link();
|
|
if (!Token::simpleMatch(tok, ") {"))
|
|
continue;
|
|
tok = tok->next();
|
|
|
|
// Search within main() for possible buffer overruns involving argv
|
|
int indentlevel = -1;
|
|
for (; tok; tok = tok->next())
|
|
{
|
|
if (tok->str() == "{")
|
|
{
|
|
++indentlevel;
|
|
}
|
|
|
|
else if (tok->str() == "}")
|
|
{
|
|
--indentlevel;
|
|
if (indentlevel < 0)
|
|
return;
|
|
}
|
|
|
|
// If argv is modified or tested, its size may be being limited properly
|
|
if (tok->varId() == varid)
|
|
break;
|
|
|
|
// Match common patterns that can result in a buffer overrun
|
|
// e.g. strcpy(buffer, argv[0])
|
|
if (Token::Match(tok, "strcpy|strcat ( %var% , * %varid%", varid) ||
|
|
Token::Match(tok, "strcpy|strcat ( %var% , %varid% [", varid))
|
|
{
|
|
cmdLineArgsError(tok);
|
|
}
|
|
else if (Token::Match(tok, "sprintf ( %var% , %str% , %varid% [", varid) &&
|
|
tok->tokAt(4)->str().find("%s") != std::string::npos)
|
|
{
|
|
cmdLineArgsError(tok);
|
|
}
|
|
else if (Token::Match(tok, "sprintf ( %var% , %str% , * %varid%", varid) &&
|
|
tok->tokAt(4)->str().find("%s") != std::string::npos)
|
|
{
|
|
cmdLineArgsError(tok);
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
}
|
|
//---------------------------------------------------------------------------
|
|
|
|
|
|
void CheckBufferOverrun::negativeIndexError(const Token *tok, MathLib::bigint index)
|
|
{
|
|
std::ostringstream ostr;
|
|
ostr << "Array index " << index << " is out of bounds";
|
|
reportError(tok, Severity::error, "negativeIndex", ostr.str());
|
|
}
|
|
|
|
void CheckBufferOverrun::negativeIndex()
|
|
{
|
|
const char pattern[] = "[ %num% ]";
|
|
for (const Token *tok = Token::findmatch(_tokenizer->tokens(), pattern); tok; tok = Token::findmatch(tok->next(),pattern))
|
|
{
|
|
const MathLib::bigint index = MathLib::toLongNumber(tok->next()->str());
|
|
if (index < 0)
|
|
{
|
|
// Negative index. Check if it's an array.
|
|
const Token *tok2 = tok;
|
|
while (Token::simpleMatch(tok2->previous(), "]"))
|
|
tok2 = tok2->previous()->link();
|
|
|
|
if (tok2->previous() && tok2->previous()->varId())
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(tok2->previous()->varId());
|
|
if (var && var->isArray())
|
|
negativeIndexError(tok, index);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
|
|
#include "executionpath.h"
|
|
|
|
/// @addtogroup Checks
|
|
/// @{
|
|
|
|
|
|
|
|
CheckBufferOverrun::ArrayInfo::ArrayInfo()
|
|
{
|
|
_element_size = 0;
|
|
_varid = 0;
|
|
}
|
|
|
|
CheckBufferOverrun::ArrayInfo::ArrayInfo(const CheckBufferOverrun::ArrayInfo &ai)
|
|
{
|
|
*this = ai;
|
|
}
|
|
|
|
CheckBufferOverrun::ArrayInfo::ArrayInfo(const Variable *var, const Tokenizer *tokenizer)
|
|
{
|
|
_varid = var->varId();
|
|
_varname = var->name();
|
|
for (size_t i = 0; i < var->dimensions().size(); i++)
|
|
_num.push_back(var->dimension(i));
|
|
if (var->typeEndToken()->str() == "*")
|
|
_element_size = tokenizer->sizeOfType(var->typeEndToken());
|
|
else if (var->typeStartToken()->str() == "struct")
|
|
_element_size = 100;
|
|
else
|
|
_element_size = tokenizer->sizeOfType(var->typeEndToken());
|
|
}
|
|
|
|
CheckBufferOverrun::ArrayInfo & CheckBufferOverrun::ArrayInfo::operator=(const CheckBufferOverrun::ArrayInfo &ai)
|
|
{
|
|
if (&ai != this)
|
|
{
|
|
_element_size = ai._element_size;
|
|
_num = ai._num;
|
|
_varid = ai._varid;
|
|
_varname = ai._varname;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
/**
|
|
* Create array info with specified data
|
|
* The intention is that this is only a temporary solution.. all
|
|
* checking should be based on ArrayInfo from the start and then
|
|
* this will not be needed as the declare can be used instead.
|
|
*/
|
|
CheckBufferOverrun::ArrayInfo::ArrayInfo(unsigned int id, const std::string &name, MathLib::bigint size1, MathLib::bigint n)
|
|
{
|
|
_element_size = size1;
|
|
_num.push_back(n);
|
|
_varid = id;
|
|
_varname = name;
|
|
}
|
|
|
|
CheckBufferOverrun::ArrayInfo CheckBufferOverrun::ArrayInfo::limit(MathLib::bigint value) const
|
|
{
|
|
MathLib::bigint uvalue = std::max(MathLib::bigint(0), value);
|
|
MathLib::bigint n = 1;
|
|
for (unsigned int i = 0; i < _num.size(); ++i)
|
|
n *= _num[i];
|
|
if (uvalue > n)
|
|
n = uvalue;
|
|
return ArrayInfo(_varid, _varname, _element_size, n - uvalue);
|
|
}
|
|
|
|
bool CheckBufferOverrun::ArrayInfo::declare(const Token *tok, const Tokenizer &tokenizer)
|
|
{
|
|
_num.clear();
|
|
_element_size = 0;
|
|
_varname.clear();
|
|
|
|
if (!tok)
|
|
return false;
|
|
|
|
if (!tok->isName() || tok->str() == "return")
|
|
return false;
|
|
|
|
while (tok && (tok->str() == "static" ||
|
|
tok->str() == "const" ||
|
|
tok->str() == "extern"))
|
|
tok = tok->next();
|
|
|
|
// ivar : number of type tokens
|
|
int ivar = 0;
|
|
if (Token::Match(tok, "%type% *| %var% ["))
|
|
ivar = 1;
|
|
else if (Token::Match(tok, "%type% %type% *| %var% ["))
|
|
ivar = 2;
|
|
else
|
|
return false;
|
|
|
|
if (tok->str().find(":") != std::string::npos)
|
|
return false;
|
|
|
|
// Goto variable name token, get element size..
|
|
const Token *vartok = tok->tokAt(ivar);
|
|
if (vartok->str() == "*")
|
|
{
|
|
_element_size = tokenizer.sizeOfType(vartok);
|
|
vartok = vartok->next();
|
|
}
|
|
else if (tok->str() == "struct")
|
|
{
|
|
_element_size = 100;
|
|
}
|
|
else
|
|
{
|
|
_element_size = tokenizer.sizeOfType(tok);
|
|
}
|
|
|
|
_varname = vartok->str();
|
|
_varid = vartok->varId();
|
|
if (!_varid)
|
|
return false;
|
|
|
|
const Token *atok = vartok->tokAt(2);
|
|
|
|
if (!Token::Match(atok, "%num% ] ;|=|["))
|
|
return false;
|
|
|
|
while (Token::Match(atok, "%num% ] ;|=|["))
|
|
{
|
|
_num.push_back(MathLib::toLongNumber(atok->str()));
|
|
atok = atok->next();
|
|
if (Token::simpleMatch(atok, "] ["))
|
|
atok = atok->tokAt(2);
|
|
}
|
|
|
|
if (Token::Match(atok, "] = !!{"))
|
|
return false;
|
|
|
|
return (!_num.empty() && Token::Match(atok, "] ;|="));
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
* @brief %Check for buffer overruns (using ExecutionPath)
|
|
*/
|
|
|
|
class ExecutionPathBufferOverrun : public ExecutionPath
|
|
{
|
|
public:
|
|
/** Startup constructor */
|
|
ExecutionPathBufferOverrun(Check *c, const std::map<unsigned int, CheckBufferOverrun::ArrayInfo> &arrayinfo)
|
|
: ExecutionPath(c, 0), arrayInfo(arrayinfo), value(0)
|
|
{
|
|
}
|
|
|
|
private:
|
|
/** @brief Copy this check. Called from the ExecutionPath baseclass. */
|
|
ExecutionPath *copy()
|
|
{
|
|
return new ExecutionPathBufferOverrun(*this);
|
|
}
|
|
|
|
/** @brief is other execution path equal? */
|
|
bool is_equal(const ExecutionPath *e) const
|
|
{
|
|
const ExecutionPathBufferOverrun *c = static_cast<const ExecutionPathBufferOverrun *>(e);
|
|
return (value == c->value);
|
|
}
|
|
|
|
/** @brief Buffer information */
|
|
const std::map<unsigned int, CheckBufferOverrun::ArrayInfo> &arrayInfo;
|
|
|
|
/** no implementation => compiler error if used by accident */
|
|
void operator=(const ExecutionPathBufferOverrun &);
|
|
|
|
/** internal constructor for creating extra checks */
|
|
ExecutionPathBufferOverrun(Check *c, const std::map<unsigned int, CheckBufferOverrun::ArrayInfo> &arrayinfo, unsigned int varid_)
|
|
: ExecutionPath(c, varid_),
|
|
arrayInfo(arrayinfo)
|
|
{
|
|
// Pretend that variables are initialized to 0
|
|
// This checking is not about uninitialized variables
|
|
value = 0;
|
|
}
|
|
|
|
/** @brief Variable value. */
|
|
MathLib::bigint value;
|
|
|
|
/**
|
|
* @brief Assign value to a variable
|
|
* @param checks the execution paths
|
|
* @param varid the variable id
|
|
* @param value the assigned value
|
|
*/
|
|
static void assign_value(std::list<ExecutionPath *> &checks, unsigned int varid, const std::string &value)
|
|
{
|
|
if (varid == 0)
|
|
return;
|
|
|
|
std::list<ExecutionPath *>::const_iterator it;
|
|
for (it = checks.begin(); it != checks.end(); ++it)
|
|
{
|
|
ExecutionPathBufferOverrun *c = dynamic_cast<ExecutionPathBufferOverrun *>(*it);
|
|
if (c && c->varId == varid)
|
|
c->value = MathLib::toLongNumber(value);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @brief Found array usage, analyse the array usage
|
|
* @param tok token where usage occurs (only used when reporting the error)
|
|
* @param checks The execution paths
|
|
* @param varid1 variable id for the array
|
|
* @param varid2 variable id for the index
|
|
*/
|
|
static void array_index(const Token *tok, std::list<ExecutionPath *> &checks, unsigned int varid1, unsigned int varid2)
|
|
{
|
|
if (checks.empty() || varid1 == 0 || varid2 == 0)
|
|
return;
|
|
|
|
// Locate array info corresponding to varid1
|
|
CheckBufferOverrun::ArrayInfo ai;
|
|
{
|
|
ExecutionPathBufferOverrun *c = dynamic_cast<ExecutionPathBufferOverrun *>(checks.front());
|
|
std::map<unsigned int, CheckBufferOverrun::ArrayInfo>::const_iterator it;
|
|
it = c->arrayInfo.find(varid1);
|
|
if (it == c->arrayInfo.end())
|
|
return;
|
|
ai = it->second;
|
|
}
|
|
|
|
// Check if varid2 variable has a value that is out-of-bounds
|
|
std::list<ExecutionPath *>::const_iterator it;
|
|
for (it = checks.begin(); it != checks.end(); ++it)
|
|
{
|
|
ExecutionPathBufferOverrun *c = dynamic_cast<ExecutionPathBufferOverrun *>(*it);
|
|
if (c && c->varId == varid2 && c->value >= ai.num(0))
|
|
{
|
|
// variable value is out of bounds, report error
|
|
CheckBufferOverrun *checkBufferOverrun = dynamic_cast<CheckBufferOverrun *>(c->owner);
|
|
if (checkBufferOverrun)
|
|
{
|
|
std::vector<MathLib::bigint> index;
|
|
index.push_back(c->value);
|
|
checkBufferOverrun->arrayIndexOutOfBounds(tok, ai, index);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
const Token *parse(const Token &tok, std::list<ExecutionPath *> &checks) const
|
|
{
|
|
if (Token::Match(tok.previous(), "[;{}]"))
|
|
{
|
|
// Declaring variable..
|
|
if (Token::Match(&tok, "%type% %var% ;") && tok.isStandardType())
|
|
{
|
|
checks.push_back(new ExecutionPathBufferOverrun(owner, arrayInfo, tok.next()->varId()));
|
|
return tok.tokAt(2);
|
|
}
|
|
|
|
// Assign variable..
|
|
if (Token::Match(&tok, "%var% = %num% ;"))
|
|
{
|
|
assign_value(checks, tok.varId(), tok.strAt(2));
|
|
return tok.tokAt(3);
|
|
}
|
|
}
|
|
|
|
// Assign variable (unknown value = 0)..
|
|
if (Token::Match(&tok, "%var% ="))
|
|
{
|
|
assign_value(checks, tok.varId(), "0");
|
|
return &tok;
|
|
}
|
|
|
|
// Assign variable (unknown value = 0)..
|
|
if (Token::Match(tok.tokAt(-2), "(|, & %var% ,|)"))
|
|
{
|
|
assign_value(checks, tok.varId(), "0");
|
|
return &tok;
|
|
}
|
|
|
|
// Array index..
|
|
if (Token::Match(&tok, "%var% [ %var% ]"))
|
|
{
|
|
array_index(&tok, checks, tok.varId(), tok.tokAt(2)->varId());
|
|
return tok.tokAt(3);
|
|
}
|
|
|
|
return &tok;
|
|
}
|
|
};
|
|
|
|
/// @}
|
|
|
|
|
|
void CheckBufferOverrun::executionPaths()
|
|
{
|
|
// Parse all variables and extract array info..
|
|
std::map<unsigned int, ArrayInfo> arrayInfo;
|
|
for (size_t i = 1; i <= _tokenizer->varIdCount(); i++)
|
|
{
|
|
const Variable *var = _tokenizer->getSymbolDatabase()->getVariableFromVarId(i);
|
|
if (var && var->isArray() && var->dimension(0) > 0)
|
|
arrayInfo[i] = ArrayInfo(var, _tokenizer);
|
|
}
|
|
|
|
// Perform checking - check how the arrayInfo arrays are used
|
|
ExecutionPathBufferOverrun c(this, arrayInfo);
|
|
checkExecutionPaths(_tokenizer->tokens(), &c);
|
|
}
|
|
|
|
|
|
|
|
|
|
void CheckBufferOverrun::arrayIndexThenCheck()
|
|
{
|
|
if (!_settings->isEnabled("style"))
|
|
return;
|
|
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())
|
|
{
|
|
if (Token::Match(tok, "%var% [ %var% ]"))
|
|
{
|
|
const std::string arrayName(tok->str());
|
|
const std::string indexName(tok->strAt(2));
|
|
|
|
// skip array index..
|
|
tok = tok->tokAt(4);
|
|
while (tok->str() == "[")
|
|
tok = tok->link()->next();
|
|
|
|
// skip comparison
|
|
if (Token::Match(tok, "==|!=|<|<=|>|>= %any% &&"))
|
|
tok = tok->tokAt(2);
|
|
|
|
// check if array index is ok
|
|
if (Token::Match(tok, ("&& " + indexName + " <|<=").c_str()))
|
|
arrayIndexThenCheckError(tok, indexName);
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckBufferOverrun::arrayIndexThenCheckError(const Token *tok, const std::string &indexName)
|
|
{
|
|
reportError(tok, Severity::style, "arrayIndexThenCheck",
|
|
"Array index " + indexName + " is used before limits check\n"
|
|
"Defensive programming: The variable " + indexName + " is used as array index and then there is a check that it is within limits. This can "
|
|
"mean that the array might be accessed out-of-bounds. Reorder conditions such as '(a[i] && i < 10)' to '(i < 10 && a[i])'. That way the "
|
|
"array will not be accessed when the index is out of limits.");
|
|
}
|