982 lines
41 KiB
C++
982 lines
41 KiB
C++
/*
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* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2021 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 "astutils.h"
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#include "errorlogger.h"
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#include "library.h"
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#include "mathlib.h"
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#include "settings.h"
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#include "symboldatabase.h"
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#include "token.h"
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#include "tokenize.h"
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#include "utils.h"
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#include "valueflow.h"
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#include <algorithm>
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#include <cstdlib>
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#include <iterator>
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#include <numeric> // std::accumulate
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#include <sstream>
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#include <tinyxml2.h>
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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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CheckBufferOverrun instance;
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}
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//---------------------------------------------------------------------------
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// CWE ids used:
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static const CWE CWE131(131U); // Incorrect Calculation of Buffer Size
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static const CWE CWE170(170U); // Improper Null Termination
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static const CWE CWE_ARRAY_INDEX_THEN_CHECK(398U); // Indicator of Poor Code Quality
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static const CWE CWE682(682U); // Incorrect Calculation
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static const CWE CWE758(758U); // Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
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static const CWE CWE_POINTER_ARITHMETIC_OVERFLOW(758U); // Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
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static const CWE CWE_BUFFER_UNDERRUN(786U); // Access of Memory Location Before Start of Buffer
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static const CWE CWE_BUFFER_OVERRUN(788U); // Access of Memory Location After End of Buffer
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//---------------------------------------------------------------------------
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static const ValueFlow::Value *getBufferSizeValue(const Token *tok)
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{
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const std::list<ValueFlow::Value> &tokenValues = tok->values();
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const auto it = std::find_if(tokenValues.begin(), tokenValues.end(), std::mem_fn(&ValueFlow::Value::isBufferSizeValue));
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return it == tokenValues.end() ? nullptr : &*it;
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}
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static int getMinFormatStringOutputLength(const std::vector<const Token*> ¶meters, nonneg int formatStringArgNr)
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{
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if (formatStringArgNr <= 0 || formatStringArgNr > parameters.size())
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return 0;
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if (parameters[formatStringArgNr - 1]->tokType() != Token::eString)
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return 0;
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const std::string &formatString = parameters[formatStringArgNr - 1]->str();
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bool percentCharFound = false;
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int outputStringSize = 0;
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bool handleNextParameter = false;
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std::string digits_string;
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bool i_d_x_f_found = false;
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int parameterLength = 0;
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int inputArgNr = formatStringArgNr;
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for (int i = 1; i + 1 < formatString.length(); ++i) {
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if (formatString[i] == '\\') {
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if (i < formatString.length() - 1 && formatString[i + 1] == '0')
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break;
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++outputStringSize;
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++i;
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continue;
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}
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if (percentCharFound) {
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switch (formatString[i]) {
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case 'f':
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case 'x':
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case 'X':
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case 'i':
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i_d_x_f_found = true;
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handleNextParameter = true;
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parameterLength = 1; // TODO
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break;
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case 'c':
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case 'e':
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case 'E':
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case 'g':
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case 'o':
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case 'u':
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case 'p':
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case 'n':
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handleNextParameter = true;
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parameterLength = 1; // TODO
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break;
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case 'd':
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i_d_x_f_found = true;
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parameterLength = 1;
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if (inputArgNr < parameters.size() && parameters[inputArgNr]->hasKnownIntValue())
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parameterLength = MathLib::toString(parameters[inputArgNr]->getKnownIntValue()).length();
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handleNextParameter = true;
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break;
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case 's':
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parameterLength = 0;
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if (inputArgNr < parameters.size() && parameters[inputArgNr]->tokType() == Token::eString)
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parameterLength = Token::getStrLength(parameters[inputArgNr]);
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handleNextParameter = true;
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break;
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}
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}
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if (formatString[i] == '%')
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percentCharFound = !percentCharFound;
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else if (percentCharFound) {
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digits_string.append(1, formatString[i]);
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}
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if (!percentCharFound)
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outputStringSize++;
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if (handleNextParameter) {
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int tempDigits = std::abs(std::atoi(digits_string.c_str()));
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if (i_d_x_f_found)
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tempDigits = std::max(tempDigits, 1);
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if (digits_string.find('.') != std::string::npos) {
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const std::string endStr = digits_string.substr(digits_string.find('.') + 1);
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const int maxLen = std::max(std::abs(std::atoi(endStr.c_str())), 1);
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if (formatString[i] == 's') {
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// For strings, the length after the dot "%.2s" will limit
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// the length of the string.
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if (parameterLength > maxLen)
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parameterLength = maxLen;
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} else {
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// For integers, the length after the dot "%.2d" can
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// increase required length
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if (tempDigits < maxLen)
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tempDigits = maxLen;
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}
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}
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if (tempDigits < parameterLength)
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outputStringSize += parameterLength;
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else
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outputStringSize += tempDigits;
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parameterLength = 0;
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digits_string.clear();
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i_d_x_f_found = false;
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percentCharFound = false;
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handleNextParameter = false;
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++inputArgNr;
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}
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}
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return outputStringSize;
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}
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//---------------------------------------------------------------------------
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static bool getDimensionsEtc(const Token * const arrayToken, const Settings *settings, std::vector<Dimension> * const dimensions, ErrorPath * const errorPath, bool * const mightBeLarger, MathLib::bigint* path)
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{
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const Token *array = arrayToken;
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while (Token::Match(array, ".|::"))
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array = array->astOperand2();
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if (array->variable() && array->variable()->isArray() && !array->variable()->dimensions().empty()) {
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*dimensions = array->variable()->dimensions();
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if (dimensions->size() >= 1 && ((*dimensions)[0].num <= 1 || !(*dimensions)[0].tok)) {
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visitAstNodes(arrayToken,
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[&](const Token *child) {
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if (child->originalName() == "->") {
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*mightBeLarger = true;
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return ChildrenToVisit::none;
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}
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return ChildrenToVisit::op1_and_op2;
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});
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}
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} else if (const Token *stringLiteral = array->getValueTokenMinStrSize(settings)) {
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Dimension dim;
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dim.tok = nullptr;
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dim.num = Token::getStrArraySize(stringLiteral);
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dim.known = array->hasKnownValue();
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dimensions->emplace_back(dim);
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} else if (array->valueType() && array->valueType()->pointer >= 1 && (array->valueType()->isIntegral() || array->valueType()->isFloat())) {
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const ValueFlow::Value *value = getBufferSizeValue(array);
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if (!value)
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return false;
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if (path)
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*path = value->path;
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*errorPath = value->errorPath;
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Dimension dim;
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dim.known = value->isKnown();
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dim.tok = nullptr;
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const int typeSize = array->valueType()->typeSize(*settings);
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if (typeSize == 0)
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return false;
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dim.num = value->intvalue / typeSize;
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dimensions->emplace_back(dim);
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}
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return !dimensions->empty();
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}
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static std::vector<const ValueFlow::Value *> getOverrunIndexValues(const Token *tok, const Token *arrayToken, const std::vector<Dimension> &dimensions, const std::vector<const Token *> &indexTokens, MathLib::bigint path)
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{
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const Token *array = arrayToken;
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while (Token::Match(array, ".|::"))
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array = array->astOperand2();
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for (int cond = 0; cond < 2; cond++) {
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bool equal = false;
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bool overflow = false;
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bool allKnown = true;
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std::vector<const ValueFlow::Value *> indexValues;
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for (int i = 0; i < dimensions.size() && i < indexTokens.size(); ++i) {
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const ValueFlow::Value *value = indexTokens[i]->getMaxValue(cond == 1);
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indexValues.push_back(value);
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if (!value)
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continue;
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if (value->path != path)
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continue;
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if (!value->isKnown()) {
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if (!allKnown)
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continue;
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allKnown = false;
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}
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if (array->variable() && array->variable()->isArray() && dimensions[i].num == 0)
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continue;
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if (value->intvalue == dimensions[i].num)
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equal = true;
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else if (value->intvalue > dimensions[i].num)
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overflow = true;
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}
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if (equal && tok->str() != "[")
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continue;
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if (!overflow && equal) {
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const Token *parent = tok;
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while (Token::simpleMatch(parent, "["))
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parent = parent->astParent();
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if (!parent || parent->isUnaryOp("&"))
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continue;
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}
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if (overflow || equal)
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return indexValues;
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}
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return std::vector<const ValueFlow::Value *>();
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}
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void CheckBufferOverrun::arrayIndex()
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{
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for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
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if (tok->str() != "[")
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continue;
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const Token *array = tok->astOperand1();
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while (Token::Match(array, ".|::"))
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array = array->astOperand2();
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if (!array || ((!array->variable() || array->variable()->nameToken() == array) && array->tokType() != Token::eString))
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continue;
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if (!array->scope()->isExecutable()) {
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// LHS in non-executable scope => This is just a definition
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const Token *parent = tok;
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while (parent && !Token::simpleMatch(parent->astParent(), "="))
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parent = parent->astParent();
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if (!parent || parent == parent->astParent()->astOperand1())
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continue;
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}
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if (astIsContainer(array))
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continue;
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std::vector<const Token *> indexTokens;
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for (const Token *tok2 = tok; tok2 && tok2->str() == "["; tok2 = tok2->link()->next()) {
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if (!tok2->astOperand2()) {
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indexTokens.clear();
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break;
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}
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indexTokens.emplace_back(tok2->astOperand2());
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}
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if (indexTokens.empty())
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continue;
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std::vector<Dimension> dimensions;
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ErrorPath errorPath;
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bool mightBeLarger = false;
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MathLib::bigint path = 0;
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if (!getDimensionsEtc(tok->astOperand1(), mSettings, &dimensions, &errorPath, &mightBeLarger, &path))
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continue;
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// Positive index
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if (!mightBeLarger) { // TODO check arrays with dim 1 also
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const std::vector<const ValueFlow::Value *> &indexValues = getOverrunIndexValues(tok, tok->astOperand1(), dimensions, indexTokens, path);
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if (!indexValues.empty())
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arrayIndexError(tok, dimensions, indexValues);
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}
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// Negative index
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bool neg = false;
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std::vector<const ValueFlow::Value *> negativeIndexes;
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for (const Token * indexToken : indexTokens) {
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const ValueFlow::Value *negativeValue = indexToken->getValueLE(-1, mSettings);
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negativeIndexes.emplace_back(negativeValue);
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if (negativeValue)
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neg = true;
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}
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if (neg) {
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negativeIndexError(tok, dimensions, negativeIndexes);
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}
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}
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}
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static std::string stringifyIndexes(const std::string &array, const std::vector<const ValueFlow::Value *> &indexValues)
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{
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if (indexValues.size() == 1)
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return MathLib::toString(indexValues[0]->intvalue);
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std::ostringstream ret;
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ret << array;
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for (const ValueFlow::Value *index : indexValues) {
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ret << "[";
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if (index)
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ret << index->intvalue;
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else
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ret << "*";
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ret << "]";
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}
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return ret.str();
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}
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static std::string arrayIndexMessage(const Token *tok, const std::vector<Dimension> &dimensions, const std::vector<const ValueFlow::Value *> &indexValues, const Token *condition)
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{
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auto add_dim = [](const std::string &s, const Dimension &dim) {
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return s + "[" + MathLib::toString(dim.num) + "]";
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};
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const std::string array = std::accumulate(dimensions.begin(), dimensions.end(), tok->astOperand1()->expressionString(), add_dim);
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std::ostringstream errmsg;
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if (condition)
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errmsg << ValueFlow::eitherTheConditionIsRedundant(condition)
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<< " or the array '" + array + "' is accessed at index " << stringifyIndexes(tok->astOperand1()->expressionString(), indexValues) << ", which is out of bounds.";
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else
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errmsg << "Array '" << array << "' accessed at index " << stringifyIndexes(tok->astOperand1()->expressionString(), indexValues) << ", which is out of bounds.";
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return errmsg.str();
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}
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void CheckBufferOverrun::arrayIndexError(const Token *tok, const std::vector<Dimension> &dimensions, const std::vector<const ValueFlow::Value *> &indexes)
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{
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if (!tok) {
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reportError(tok, Severity::error, "arrayIndexOutOfBounds", "Array 'arr[16]' accessed at index 16, which is out of bounds.", CWE_BUFFER_OVERRUN, Certainty::normal);
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reportError(tok, Severity::warning, "arrayIndexOutOfBoundsCond", "Array 'arr[16]' accessed at index 16, which is out of bounds.", CWE_BUFFER_OVERRUN, Certainty::normal);
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return;
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}
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const Token *condition = nullptr;
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const ValueFlow::Value *index = nullptr;
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for (const ValueFlow::Value *indexValue: indexes) {
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if (!indexValue)
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continue;
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if (!indexValue->errorSeverity() && !mSettings->severity.isEnabled(Severity::warning))
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return;
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if (indexValue->condition)
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condition = indexValue->condition;
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if (!index || !indexValue->errorPath.empty())
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index = indexValue;
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}
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reportError(getErrorPath(tok, index, "Array index out of bounds"),
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index->errorSeverity() ? Severity::error : Severity::warning,
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index->condition ? "arrayIndexOutOfBoundsCond" : "arrayIndexOutOfBounds",
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arrayIndexMessage(tok, dimensions, indexes, condition),
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CWE_BUFFER_OVERRUN,
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index->isInconclusive() ? Certainty::inconclusive : Certainty::normal);
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}
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void CheckBufferOverrun::negativeIndexError(const Token *tok, const std::vector<Dimension> &dimensions, const std::vector<const ValueFlow::Value *> &indexes)
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{
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if (!tok) {
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reportError(tok, Severity::error, "negativeIndex", "Negative array index", CWE_BUFFER_UNDERRUN, Certainty::normal);
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return;
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}
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const Token *condition = nullptr;
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const ValueFlow::Value *negativeValue = nullptr;
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for (const ValueFlow::Value *indexValue: indexes) {
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if (!indexValue)
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continue;
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if (!indexValue->errorSeverity() && !mSettings->severity.isEnabled(Severity::warning))
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return;
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if (indexValue->condition)
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condition = indexValue->condition;
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if (!negativeValue || !indexValue->errorPath.empty())
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negativeValue = indexValue;
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}
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reportError(getErrorPath(tok, negativeValue, "Negative array index"),
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negativeValue->errorSeverity() ? Severity::error : Severity::warning,
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"negativeIndex",
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arrayIndexMessage(tok, dimensions, indexes, condition),
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CWE_BUFFER_UNDERRUN,
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negativeValue->isInconclusive() ? Certainty::inconclusive : Certainty::normal);
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}
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//---------------------------------------------------------------------------
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void CheckBufferOverrun::pointerArithmetic()
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{
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if (!mSettings->severity.isEnabled(Severity::portability))
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return;
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for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
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if (!Token::Match(tok, "+|-"))
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continue;
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if (!tok->valueType() || tok->valueType()->pointer == 0)
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continue;
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if (!tok->isBinaryOp())
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continue;
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if (!tok->astOperand1()->valueType() || !tok->astOperand2()->valueType())
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continue;
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const Token *arrayToken, *indexToken;
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if (tok->astOperand1()->valueType()->pointer > 0) {
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arrayToken = tok->astOperand1();
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indexToken = tok->astOperand2();
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} else {
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arrayToken = tok->astOperand2();
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indexToken = tok->astOperand1();
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}
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if (!indexToken || !indexToken->valueType() || indexToken->valueType()->pointer > 0 || !indexToken->valueType()->isIntegral())
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continue;
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std::vector<Dimension> dimensions;
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ErrorPath errorPath;
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bool mightBeLarger = false;
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MathLib::bigint path = 0;
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if (!getDimensionsEtc(arrayToken, mSettings, &dimensions, &errorPath, &mightBeLarger, &path))
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continue;
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if (tok->str() == "+") {
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// Positive index
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if (!mightBeLarger) { // TODO check arrays with dim 1 also
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const std::vector<const Token *> indexTokens{indexToken};
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const std::vector<const ValueFlow::Value *> &indexValues = getOverrunIndexValues(tok, arrayToken, dimensions, indexTokens, path);
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if (!indexValues.empty())
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pointerArithmeticError(tok, indexToken, indexValues.front());
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}
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if (const ValueFlow::Value *neg = indexToken->getValueLE(-1, mSettings))
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pointerArithmeticError(tok, indexToken, neg);
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} else if (tok->str() == "-") {
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const Token *array = arrayToken;
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while (Token::Match(array, ".|::"))
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array = array->astOperand2();
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if (array->variable() && array->variable()->isArray()) {
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const ValueFlow::Value *v = indexToken->getValueGE(1, mSettings);
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if (v)
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pointerArithmeticError(tok, indexToken, v);
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}
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}
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}
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}
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void CheckBufferOverrun::pointerArithmeticError(const Token *tok, const Token *indexToken, const ValueFlow::Value *indexValue)
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{
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if (!tok) {
|
|
reportError(tok, Severity::portability, "pointerOutOfBounds", "Pointer arithmetic overflow.", CWE_POINTER_ARITHMETIC_OVERFLOW, Certainty::normal);
|
|
reportError(tok, Severity::portability, "pointerOutOfBoundsCond", "Pointer arithmetic overflow.", CWE_POINTER_ARITHMETIC_OVERFLOW, Certainty::normal);
|
|
return;
|
|
}
|
|
|
|
std::string errmsg;
|
|
if (indexValue->condition)
|
|
errmsg = "Undefined behaviour, when '" + indexToken->expressionString() + "' is " + MathLib::toString(indexValue->intvalue) + " the pointer arithmetic '" + tok->expressionString() + "' is out of bounds.";
|
|
else
|
|
errmsg = "Undefined behaviour, pointer arithmetic '" + tok->expressionString() + "' is out of bounds.";
|
|
|
|
reportError(getErrorPath(tok, indexValue, "Pointer arithmetic overflow"),
|
|
Severity::portability,
|
|
indexValue->condition ? "pointerOutOfBoundsCond" : "pointerOutOfBounds",
|
|
errmsg,
|
|
CWE_POINTER_ARITHMETIC_OVERFLOW,
|
|
indexValue->isInconclusive() ? Certainty::inconclusive : Certainty::normal);
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
ValueFlow::Value CheckBufferOverrun::getBufferSize(const Token *bufTok) const
|
|
{
|
|
if (!bufTok->valueType())
|
|
return ValueFlow::Value(-1);
|
|
const Variable *var = bufTok->variable();
|
|
|
|
if (!var || var->dimensions().empty()) {
|
|
const ValueFlow::Value *value = getBufferSizeValue(bufTok);
|
|
if (value)
|
|
return *value;
|
|
}
|
|
|
|
if (!var)
|
|
return ValueFlow::Value(-1);
|
|
|
|
MathLib::bigint dim = std::accumulate(var->dimensions().begin(), var->dimensions().end(), 1LL, [](MathLib::bigint i1, const Dimension &dim) {
|
|
return i1 * dim.num;
|
|
});
|
|
|
|
ValueFlow::Value v;
|
|
v.setKnown();
|
|
v.valueType = ValueFlow::Value::ValueType::BUFFER_SIZE;
|
|
|
|
if (var->isPointerArray())
|
|
v.intvalue = dim * mSettings->sizeof_pointer;
|
|
else if (var->isPointer())
|
|
return ValueFlow::Value(-1);
|
|
else {
|
|
const MathLib::bigint typeSize = bufTok->valueType()->typeSize(*mSettings);
|
|
v.intvalue = dim * typeSize;
|
|
}
|
|
|
|
return v;
|
|
}
|
|
//---------------------------------------------------------------------------
|
|
|
|
static bool checkBufferSize(const Token *ftok, const Library::ArgumentChecks::MinSize &minsize, const std::vector<const Token *> &args, const MathLib::bigint bufferSize, const Settings *settings)
|
|
{
|
|
const Token * const arg = (minsize.arg > 0 && minsize.arg - 1 < args.size()) ? args[minsize.arg - 1] : nullptr;
|
|
const Token * const arg2 = (minsize.arg2 > 0 && minsize.arg2 - 1 < args.size()) ? args[minsize.arg2 - 1] : nullptr;
|
|
|
|
switch (minsize.type) {
|
|
case Library::ArgumentChecks::MinSize::Type::STRLEN:
|
|
if (settings->library.isargformatstr(ftok, minsize.arg)) {
|
|
return getMinFormatStringOutputLength(args, minsize.arg) < bufferSize;
|
|
} else if (arg) {
|
|
const Token *strtoken = arg->getValueTokenMaxStrLength();
|
|
if (strtoken)
|
|
return Token::getStrLength(strtoken) < bufferSize;
|
|
}
|
|
break;
|
|
case Library::ArgumentChecks::MinSize::Type::ARGVALUE:
|
|
if (arg && arg->hasKnownIntValue())
|
|
return arg->getKnownIntValue() <= bufferSize;
|
|
break;
|
|
case Library::ArgumentChecks::MinSize::Type::SIZEOF:
|
|
// TODO
|
|
break;
|
|
case Library::ArgumentChecks::MinSize::Type::MUL:
|
|
if (arg && arg2 && arg->hasKnownIntValue() && arg2->hasKnownIntValue())
|
|
return (arg->getKnownIntValue() * arg2->getKnownIntValue()) <= bufferSize;
|
|
break;
|
|
case Library::ArgumentChecks::MinSize::Type::VALUE:
|
|
return minsize.value <= bufferSize;
|
|
case Library::ArgumentChecks::MinSize::Type::NONE:
|
|
break;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
|
|
void CheckBufferOverrun::bufferOverflow()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
|
|
for (const Scope * scope : symbolDatabase->functionScopes) {
|
|
for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
|
|
if (!Token::Match(tok, "%name% (") || Token::simpleMatch(tok, ") {"))
|
|
continue;
|
|
if (!mSettings->library.hasminsize(tok))
|
|
continue;
|
|
const std::vector<const Token *> args = getArguments(tok);
|
|
for (int argnr = 0; argnr < args.size(); ++argnr) {
|
|
if (!args[argnr]->valueType() || args[argnr]->valueType()->pointer == 0)
|
|
continue;
|
|
const std::vector<Library::ArgumentChecks::MinSize> *minsizes = mSettings->library.argminsizes(tok, argnr + 1);
|
|
if (!minsizes || minsizes->empty())
|
|
continue;
|
|
// Get buffer size..
|
|
const Token *argtok = args[argnr];
|
|
while (argtok && argtok->isCast())
|
|
argtok = argtok->astOperand2() ? argtok->astOperand2() : argtok->astOperand1();
|
|
while (Token::Match(argtok, ".|::"))
|
|
argtok = argtok->astOperand2();
|
|
if (!argtok || !argtok->variable())
|
|
continue;
|
|
if (argtok->valueType() && argtok->valueType()->pointer == 0)
|
|
continue;
|
|
// TODO: strcpy(buf+10, "hello");
|
|
const ValueFlow::Value bufferSize = getBufferSize(argtok);
|
|
if (bufferSize.intvalue <= 0)
|
|
continue;
|
|
// buffer size == 1 => do not warn for dynamic memory
|
|
if (bufferSize.intvalue == 1) {
|
|
const Token *tok2 = argtok;
|
|
while (Token::simpleMatch(tok2->astParent(), "."))
|
|
tok2 = tok2->astParent();
|
|
while (Token::Match(tok2, "[|."))
|
|
tok2 = tok2->astOperand1();
|
|
const Variable *var = tok2 ? tok2->variable() : nullptr;
|
|
if (var) {
|
|
if (var->isPointer())
|
|
continue;
|
|
if (var->isArgument() && var->isReference())
|
|
continue;
|
|
}
|
|
}
|
|
const bool error = std::none_of(minsizes->begin(), minsizes->end(), [=](const Library::ArgumentChecks::MinSize &minsize) {
|
|
return checkBufferSize(tok, minsize, args, bufferSize.intvalue, mSettings);
|
|
});
|
|
if (error)
|
|
bufferOverflowError(args[argnr], &bufferSize, (bufferSize.intvalue == 1) ? Certainty::inconclusive : Certainty::normal);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckBufferOverrun::bufferOverflowError(const Token *tok, const ValueFlow::Value *value, const Certainty::CertaintyLevel &certainty)
|
|
{
|
|
reportError(getErrorPath(tok, value, "Buffer overrun"), Severity::error, "bufferAccessOutOfBounds", "Buffer is accessed out of bounds: " + (tok ? tok->expressionString() : "buf"), CWE_BUFFER_OVERRUN, certainty);
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckBufferOverrun::arrayIndexThenCheck()
|
|
{
|
|
if (!mSettings->severity.isEnabled(Severity::portability))
|
|
return;
|
|
|
|
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
|
|
for (const Scope * const scope : symbolDatabase->functionScopes) {
|
|
for (const Token *tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) {
|
|
if (Token::simpleMatch(tok, "sizeof (")) {
|
|
tok = tok->linkAt(1);
|
|
continue;
|
|
}
|
|
|
|
if (Token::Match(tok, "%name% [ %var% ]")) {
|
|
tok = tok->next();
|
|
|
|
const int indexID = tok->next()->varId();
|
|
const std::string& indexName(tok->strAt(1));
|
|
|
|
// Iterate AST upwards
|
|
const Token* tok2 = tok;
|
|
const Token* tok3 = tok2;
|
|
while (tok2->astParent() && tok2->tokType() != Token::eLogicalOp && tok2->str() != "?") {
|
|
tok3 = tok2;
|
|
tok2 = tok2->astParent();
|
|
}
|
|
|
|
// Ensure that we ended at a logical operator and that we came from its left side
|
|
if (tok2->tokType() != Token::eLogicalOp || tok2->astOperand1() != tok3)
|
|
continue;
|
|
|
|
// check if array index is ok
|
|
// statement can be closed in parentheses, so "(| " is using
|
|
if (Token::Match(tok2, "&& (| %varid% <|<=", indexID))
|
|
arrayIndexThenCheckError(tok, indexName);
|
|
else if (Token::Match(tok2, "&& (| %any% >|>= %varid% !!+", indexID))
|
|
arrayIndexThenCheckError(tok, indexName);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckBufferOverrun::arrayIndexThenCheckError(const Token *tok, const std::string &indexName)
|
|
{
|
|
reportError(tok, Severity::style, "arrayIndexThenCheck",
|
|
"$symbol:" + indexName + "\n"
|
|
"Array index '$symbol' is used before limits check.\n"
|
|
"Defensive programming: The variable '$symbol' is used as an array index before it "
|
|
"is checked that 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 if the index is out of limits.", CWE_ARRAY_INDEX_THEN_CHECK, Certainty::normal);
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
|
|
void CheckBufferOverrun::stringNotZeroTerminated()
|
|
{
|
|
// this is currently 'inconclusive'. See TestBufferOverrun::terminateStrncpy3
|
|
if (!mSettings->severity.isEnabled(Severity::warning) || !mSettings->certainty.isEnabled(Certainty::inconclusive))
|
|
return;
|
|
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
|
|
for (const Scope * const scope : symbolDatabase->functionScopes) {
|
|
for (const Token *tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) {
|
|
if (!Token::simpleMatch(tok, "strncpy ("))
|
|
continue;
|
|
const std::vector<const Token *> args = getArguments(tok);
|
|
if (args.size() != 3)
|
|
continue;
|
|
const Token *sizeToken = args[2];
|
|
if (!sizeToken->hasKnownIntValue())
|
|
continue;
|
|
const ValueFlow::Value &bufferSize = getBufferSize(args[0]);
|
|
if (bufferSize.intvalue < 0 || sizeToken->getKnownIntValue() < bufferSize.intvalue)
|
|
continue;
|
|
const Token *srcValue = args[1]->getValueTokenMaxStrLength();
|
|
if (srcValue && Token::getStrLength(srcValue) < sizeToken->getKnownIntValue())
|
|
continue;
|
|
// Is the buffer zero terminated after the call?
|
|
bool isZeroTerminated = false;
|
|
for (const Token *tok2 = tok->next()->link(); tok2 != scope->bodyEnd; tok2 = tok2->next()) {
|
|
if (!Token::simpleMatch(tok2, "] ="))
|
|
continue;
|
|
const Token *rhs = tok2->next()->astOperand2();
|
|
if (!rhs || !rhs->hasKnownIntValue() || rhs->getKnownIntValue() != 0)
|
|
continue;
|
|
if (isSameExpression(mTokenizer->isCPP(), false, args[0], tok2->link()->astOperand1(), mSettings->library, false, false))
|
|
isZeroTerminated = true;
|
|
}
|
|
if (isZeroTerminated)
|
|
continue;
|
|
// TODO: Locate unsafe string usage..
|
|
terminateStrncpyError(tok, args[0]->expressionString());
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckBufferOverrun::terminateStrncpyError(const Token *tok, const std::string &varname)
|
|
{
|
|
const std::string shortMessage = "The buffer '$symbol' may not be null-terminated after the call to strncpy().";
|
|
reportError(tok, Severity::warning, "terminateStrncpy",
|
|
"$symbol:" + varname + '\n' +
|
|
shortMessage + '\n' +
|
|
shortMessage + ' ' +
|
|
"If the source string's size fits or exceeds the given size, strncpy() does not add a "
|
|
"zero at the end of the buffer. This causes bugs later in the code if the code "
|
|
"assumes buffer is null-terminated.", CWE170, Certainty::inconclusive);
|
|
}
|
|
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
// CTU..
|
|
//---------------------------------------------------------------------------
|
|
|
|
std::string CheckBufferOverrun::MyFileInfo::toString() const
|
|
{
|
|
std::string xml;
|
|
if (!unsafeArrayIndex.empty())
|
|
xml = " <array-index>\n" + CTU::toString(unsafeArrayIndex) + " </array-index>\n";
|
|
if (!unsafePointerArith.empty())
|
|
xml += " <pointer-arith>\n" + CTU::toString(unsafePointerArith) + " </pointer-arith>\n";
|
|
return xml;
|
|
}
|
|
|
|
bool CheckBufferOverrun::isCtuUnsafeBufferUsage(const Check *check, const Token *argtok, MathLib::bigint *offset, int type)
|
|
{
|
|
const CheckBufferOverrun *c = dynamic_cast<const CheckBufferOverrun *>(check);
|
|
if (!c)
|
|
return false;
|
|
if (!argtok->valueType() || argtok->valueType()->typeSize(*c->mSettings) == 0)
|
|
return false;
|
|
const Token *indexTok = nullptr;
|
|
if (type == 1 && Token::Match(argtok, "%name% [") && argtok->astParent() == argtok->next() && !Token::simpleMatch(argtok->linkAt(1), "] ["))
|
|
indexTok = argtok->next()->astOperand2();
|
|
else if (type == 2 && Token::simpleMatch(argtok->astParent(), "+"))
|
|
indexTok = (argtok == argtok->astParent()->astOperand1()) ?
|
|
argtok->astParent()->astOperand2() :
|
|
argtok->astParent()->astOperand1();
|
|
if (!indexTok)
|
|
return false;
|
|
if (!indexTok->hasKnownIntValue())
|
|
return false;
|
|
if (!offset)
|
|
return false;
|
|
*offset = indexTok->getKnownIntValue() * argtok->valueType()->typeSize(*c->mSettings);
|
|
return true;
|
|
}
|
|
|
|
bool CheckBufferOverrun::isCtuUnsafeArrayIndex(const Check *check, const Token *argtok, MathLib::bigint *offset)
|
|
{
|
|
return CheckBufferOverrun::isCtuUnsafeBufferUsage(check, argtok, offset, 1);
|
|
}
|
|
|
|
bool CheckBufferOverrun::isCtuUnsafePointerArith(const Check *check, const Token *argtok, MathLib::bigint *offset)
|
|
{
|
|
return CheckBufferOverrun::isCtuUnsafeBufferUsage(check, argtok, offset, 2);
|
|
}
|
|
|
|
/** @brief Parse current TU and extract file info */
|
|
Check::FileInfo *CheckBufferOverrun::getFileInfo(const Tokenizer *tokenizer, const Settings *settings) const
|
|
{
|
|
CheckBufferOverrun checkBufferOverrun(tokenizer, settings, nullptr);
|
|
MyFileInfo *fileInfo = new MyFileInfo;
|
|
fileInfo->unsafeArrayIndex = CTU::getUnsafeUsage(tokenizer, settings, &checkBufferOverrun, isCtuUnsafeArrayIndex);
|
|
fileInfo->unsafePointerArith = CTU::getUnsafeUsage(tokenizer, settings, &checkBufferOverrun, isCtuUnsafePointerArith);
|
|
if (fileInfo->unsafeArrayIndex.empty() && fileInfo->unsafePointerArith.empty()) {
|
|
delete fileInfo;
|
|
return nullptr;
|
|
}
|
|
return fileInfo;
|
|
}
|
|
|
|
Check::FileInfo * CheckBufferOverrun::loadFileInfoFromXml(const tinyxml2::XMLElement *xmlElement) const
|
|
{
|
|
const std::string arrayIndex("array-index");
|
|
const std::string pointerArith("pointer-arith");
|
|
|
|
MyFileInfo *fileInfo = new MyFileInfo;
|
|
for (const tinyxml2::XMLElement *e = xmlElement->FirstChildElement(); e; e = e->NextSiblingElement()) {
|
|
if (e->Name() == arrayIndex)
|
|
fileInfo->unsafeArrayIndex = CTU::loadUnsafeUsageListFromXml(e);
|
|
else if (e->Name() == pointerArith)
|
|
fileInfo->unsafePointerArith = CTU::loadUnsafeUsageListFromXml(e);
|
|
}
|
|
|
|
if (fileInfo->unsafeArrayIndex.empty() && fileInfo->unsafePointerArith.empty()) {
|
|
delete fileInfo;
|
|
return nullptr;
|
|
}
|
|
|
|
return fileInfo;
|
|
}
|
|
|
|
/** @brief Analyse all file infos for all TU */
|
|
bool CheckBufferOverrun::analyseWholeProgram(const CTU::FileInfo *ctu, const std::list<Check::FileInfo*> &fileInfo, const Settings& settings, ErrorLogger &errorLogger)
|
|
{
|
|
if (!ctu)
|
|
return false;
|
|
bool foundErrors = false;
|
|
(void)settings; // This argument is unused
|
|
|
|
const std::map<std::string, std::list<const CTU::FileInfo::CallBase *>> callsMap = ctu->getCallsMap();
|
|
|
|
for (Check::FileInfo *fi1 : fileInfo) {
|
|
const MyFileInfo *fi = dynamic_cast<MyFileInfo*>(fi1);
|
|
if (!fi)
|
|
continue;
|
|
for (const CTU::FileInfo::UnsafeUsage &unsafeUsage : fi->unsafeArrayIndex)
|
|
foundErrors |= analyseWholeProgram1(callsMap, unsafeUsage, 1, errorLogger);
|
|
for (const CTU::FileInfo::UnsafeUsage &unsafeUsage : fi->unsafePointerArith)
|
|
foundErrors |= analyseWholeProgram1(callsMap, unsafeUsage, 2, errorLogger);
|
|
}
|
|
return foundErrors;
|
|
}
|
|
|
|
bool CheckBufferOverrun::analyseWholeProgram1(const std::map<std::string, std::list<const CTU::FileInfo::CallBase *>> &callsMap, const CTU::FileInfo::UnsafeUsage &unsafeUsage, int type, ErrorLogger &errorLogger)
|
|
{
|
|
const CTU::FileInfo::FunctionCall *functionCall = nullptr;
|
|
|
|
const std::list<ErrorMessage::FileLocation> &locationList =
|
|
CTU::FileInfo::getErrorPath(CTU::FileInfo::InvalidValueType::bufferOverflow,
|
|
unsafeUsage,
|
|
callsMap,
|
|
"Using argument ARG",
|
|
&functionCall,
|
|
false);
|
|
if (locationList.empty())
|
|
return false;
|
|
|
|
const char *errorId = nullptr;
|
|
std::string errmsg;
|
|
CWE cwe(0);
|
|
|
|
if (type == 1) {
|
|
errorId = "ctuArrayIndex";
|
|
if (unsafeUsage.value > 0)
|
|
errmsg = "Array index out of bounds; '" + unsafeUsage.myArgumentName + "' buffer size is " + MathLib::toString(functionCall->callArgValue) + " and it is accessed at offset " + MathLib::toString(unsafeUsage.value) + ".";
|
|
else
|
|
errmsg = "Array index out of bounds; buffer '" + unsafeUsage.myArgumentName + "' is accessed at offset " + MathLib::toString(unsafeUsage.value) + ".";
|
|
cwe = (unsafeUsage.value > 0) ? CWE_BUFFER_OVERRUN : CWE_BUFFER_UNDERRUN;
|
|
} else {
|
|
errorId = "ctuPointerArith";
|
|
errmsg = "Pointer arithmetic overflow; '" + unsafeUsage.myArgumentName + "' buffer size is " + MathLib::toString(functionCall->callArgValue);
|
|
cwe = CWE_POINTER_ARITHMETIC_OVERFLOW;
|
|
}
|
|
|
|
const ErrorMessage errorMessage(locationList,
|
|
emptyString,
|
|
Severity::error,
|
|
errmsg,
|
|
errorId,
|
|
cwe, Certainty::normal);
|
|
errorLogger.reportErr(errorMessage);
|
|
|
|
return true;
|
|
}
|
|
|
|
void CheckBufferOverrun::objectIndex()
|
|
{
|
|
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
|
|
for (const Scope *functionScope : symbolDatabase->functionScopes) {
|
|
for (const Token *tok = functionScope->bodyStart; tok != functionScope->bodyEnd; tok = tok->next()) {
|
|
if (!Token::simpleMatch(tok, "["))
|
|
continue;
|
|
const Token *obj = tok->astOperand1();
|
|
const Token *idx = tok->astOperand2();
|
|
if (!idx || !obj)
|
|
continue;
|
|
if (idx->hasKnownIntValue()) {
|
|
if (idx->getKnownIntValue() == 0)
|
|
continue;
|
|
}
|
|
if (idx->hasKnownIntValue() && idx->getKnownIntValue() == 0)
|
|
continue;
|
|
|
|
std::vector<ValueFlow::Value> values = getLifetimeObjValues(obj, false, true);
|
|
for (const ValueFlow::Value& v:values) {
|
|
if (v.lifetimeKind != ValueFlow::Value::LifetimeKind::Address)
|
|
continue;
|
|
const Variable *var = v.tokvalue->variable();
|
|
if (var->isReference())
|
|
continue;
|
|
if (var->isRValueReference())
|
|
continue;
|
|
if (var->isArray())
|
|
continue;
|
|
if (var->isPointer()) {
|
|
if (!var->valueType())
|
|
continue;
|
|
if (!obj->valueType())
|
|
continue;
|
|
if (var->valueType()->pointer > obj->valueType()->pointer)
|
|
continue;
|
|
}
|
|
if (v.path != 0) {
|
|
std::vector<ValueFlow::Value> idxValues;
|
|
std::copy_if(idx->values().begin(),
|
|
idx->values().end(),
|
|
std::back_inserter(idxValues),
|
|
[&](const ValueFlow::Value& vidx) {
|
|
if (!vidx.isIntValue())
|
|
return false;
|
|
return vidx.path == v.path || vidx.path == 0;
|
|
});
|
|
if (idxValues.empty() ||
|
|
std::any_of(idxValues.begin(), idxValues.end(), [&](const ValueFlow::Value& vidx) {
|
|
if (vidx.isImpossible())
|
|
return (vidx.intvalue == 0);
|
|
else
|
|
return (vidx.intvalue != 0);
|
|
})) {
|
|
objectIndexError(tok, &v, idx->hasKnownIntValue());
|
|
}
|
|
} else {
|
|
objectIndexError(tok, &v, idx->hasKnownIntValue());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckBufferOverrun::objectIndexError(const Token *tok, const ValueFlow::Value *v, bool known)
|
|
{
|
|
ErrorPath errorPath;
|
|
std::string name;
|
|
if (v) {
|
|
name = v->tokvalue->variable()->name();
|
|
errorPath = v->errorPath;
|
|
}
|
|
errorPath.emplace_back(tok, "");
|
|
std::string verb = known ? "is" : "might be";
|
|
reportError(errorPath,
|
|
known ? Severity::error : Severity::warning,
|
|
"objectIndex",
|
|
"The address of local variable '" + name + "' " + verb + " accessed at non-zero index.",
|
|
CWE758,
|
|
Certainty::normal);
|
|
}
|