282 lines
12 KiB
C++
282 lines
12 KiB
C++
/*
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* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2014 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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#ifndef checkbufferoverrunH
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#define checkbufferoverrunH
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//---------------------------------------------------------------------------
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#include "config.h"
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#include "check.h"
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#include "settings.h"
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#include "mathlib.h"
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#include <list>
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#include <vector>
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#include <string>
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class ErrorLogger;
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class Token;
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class Tokenizer;
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class Variable;
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/// @addtogroup Checks
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/// @{
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/**
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* @brief buffer overruns and array index out of bounds
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*
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* Buffer overrun and array index out of bounds are pretty much the same.
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* But I generally use 'array index' if the code contains []. And the given
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* index is out of bounds.
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* I generally use 'buffer overrun' if you for example call a strcpy or
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* other function and pass a buffer and reads or writes too much data.
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*/
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class CPPCHECKLIB CheckBufferOverrun : public Check {
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public:
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/** This constructor is used when registering the CheckClass */
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CheckBufferOverrun() : Check(myName()) {
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}
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/** This constructor is used when running checks. */
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CheckBufferOverrun(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger)
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: Check(myName(), tokenizer, settings, errorLogger) {
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}
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void runSimplifiedChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) {
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CheckBufferOverrun checkBufferOverrun(tokenizer, settings, errorLogger);
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checkBufferOverrun.bufferOverrun();
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checkBufferOverrun.arrayIndexThenCheck();
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checkBufferOverrun.writeOutsideBufferSize();
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}
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/** @brief %Check for buffer overruns */
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void bufferOverrun();
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/** @brief Using array index before bounds check */
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void arrayIndexThenCheck();
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/** @brief %Check for buffer overruns by inspecting execution paths */
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void executionPaths();
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/** @brief %Check using POSIX write function and writing outside buffer size */
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void writeOutsideBufferSize();
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/**
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* @brief Get minimum length of format string result
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* @param input_string format string
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* @param parameters given parameters to sprintf
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* @return minimum length of resulting string
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*/
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static MathLib::bigint countSprintfLength(const std::string &input_string, const std::list<const Token*> ¶meters);
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/**
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* @brief %Check code that matches: "sprintf ( %varid% , %str% [,)]" when varid is not 0,
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* and report found errors.
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* @param tok The "sprintf" token.
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* @param size The size of the buffer where sprintf is writing.
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*/
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void checkSprintfCall(const Token *tok, const MathLib::bigint size);
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/** Check for buffer overruns - locate struct variables and check them with the .._CheckScope function */
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void checkStructVariable();
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/** Check for buffer overruns - locate global variables and local function variables and check them with the checkScope function */
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void checkGlobalAndLocalVariable();
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/** Check for buffer overruns due to allocating strlen(src) bytes instead of (strlen(src)+1) bytes before copying a string */
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void checkBufferAllocatedWithStrlen();
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/** Check for buffer overruns due to copying command-line args to fixed-sized buffers without bounds checking */
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void checkInsecureCmdLineArgs();
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/** Check for negative index */
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void negativeIndex();
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/** Information about N-dimensional array */
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class CPPCHECKLIB ArrayInfo {
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private:
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/** number of elements of array */
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std::vector<MathLib::bigint> _num;
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/** full name of variable as pattern */
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std::string _varname;
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/** size of each element in array */
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MathLib::bigint _element_size;
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/** declaration id */
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unsigned int _declarationId;
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public:
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ArrayInfo();
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ArrayInfo(const Variable *var, const Tokenizer *tokenizer, const unsigned int forcedeclid = 0);
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/**
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* Create array info with specified data
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* The intention is that this is only a temporary solution.. all
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* checking should be based on ArrayInfo from the start and then
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* this will not be needed as the declare can be used instead.
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*/
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ArrayInfo(unsigned int id, const std::string &name, MathLib::bigint size1, MathLib::bigint n);
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/** Create a copy ArrayInfo where the number of elements have been limited by a value */
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ArrayInfo limit(MathLib::bigint value) const;
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/** array sizes */
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const std::vector<MathLib::bigint> &num() const {
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return _num;
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}
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/** array size */
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MathLib::bigint num(std::size_t index) const {
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return _num[index];
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}
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void num(std::size_t index, MathLib::bigint number) {
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_num[index] = number;
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}
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/** size of each element */
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MathLib::bigint element_size() const {
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return _element_size;
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}
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/** Variable name */
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unsigned int declarationId() const {
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return _declarationId;
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}
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void declarationId(unsigned int id) {
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_declarationId = id;
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}
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/** Variable name */
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const std::string &varname() const {
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return _varname;
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}
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void varname(const std::string &name) {
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_varname = name;
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}
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};
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/** Check for buffer overruns (based on ArrayInfo) */
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void checkScope(const Token *tok, const ArrayInfo &arrayInfo);
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/** Check for buffer overruns */
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void checkScope(const Token *tok, const std::vector<std::string> &varname, const ArrayInfo &arrayInfo);
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/** Check scope helper function - parse for body */
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void checkScopeForBody(const Token *tok, const ArrayInfo &arrayInfo, bool &bailout);
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/** Helper function used when parsing for-loops */
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void 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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/** Check readlink or readlinkat() buffer usage */
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void checkReadlinkBufferUsage(const Token *ftok, const Token *scope_begin, const unsigned int varid, const MathLib::bigint total_size);
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/**
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* Helper function for checkFunctionCall - check a function parameter
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* \param tok token for the function name
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* \param par on what parameter is the array used
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* \param arrayInfo the array information
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* \param callstack call stack. This is used to prevent recursion and to provide better error messages. Pass a empty list from checkScope etc.
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*/
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void checkFunctionParameter(const Token &tok, const unsigned int par, const ArrayInfo &arrayInfo, std::list<const Token *> callstack);
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/**
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* Helper function that checks if the array is used and if so calls the checkFunctionCall
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* @param tok token that matches "%var% ("
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* @param arrayInfo the array information
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* \param callstack call stack. This is used to prevent recursion and to provide better error messages. Pass a empty list from checkScope etc.
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*/
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void checkFunctionCall(const Token *tok, const ArrayInfo &arrayInfo, std::list<const Token *> callstack);
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void arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index);
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void arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<ValueFlow::Value> &index);
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void arrayIndexInForLoop(const Token *tok, const ArrayInfo &arrayInfo);
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private:
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static bool isArrayOfStruct(const Token* tok, int &position);
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void arrayIndexOutOfBoundsError(const std::list<const Token *> &callstack, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index);
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void bufferOverrunError(const Token *tok, const std::string &varnames = "");
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void bufferOverrunError(const std::list<const Token *> &callstack, const std::string &varnames = "");
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void strncatUsageError(const Token *tok);
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void negativeMemoryAllocationSizeError(const Token *tok); // provide a negative value to memory allocation function
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void outOfBoundsError(const Token *tok, const std::string &what, const bool show_size_info, const MathLib::bigint &supplied_size, const MathLib::bigint &actual_size);
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void sizeArgumentAsCharError(const Token *tok);
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void terminateStrncpyError(const Token *tok, const std::string &varname);
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void bufferNotZeroTerminatedError(const Token *tok, const std::string &varname, const std::string &function);
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void negativeIndexError(const Token *tok, MathLib::bigint index);
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void negativeIndexError(const Token *tok, const ValueFlow::Value &index);
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void cmdLineArgsError(const Token *tok);
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void pointerOutOfBoundsError(const Token *tok, const std::string &object); // UB when result of calculation is out of bounds
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void arrayIndexThenCheckError(const Token *tok, const std::string &indexName);
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void possibleBufferOverrunError(const Token *tok, const std::string &src, const std::string &dst, bool cat);
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void possibleReadlinkBufferOverrunError(const Token *tok, const std::string &funcname, const std::string &varname);
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void argumentSizeError(const Token *tok, const std::string &functionName, const std::string &varname);
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void writeOutsideBufferSizeError(const Token *tok, const std::size_t stringLength, const MathLib::bigint writeLength, const std::string& functionName);
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void valueFlowCheckArrayIndex(const Token * const tok, const ArrayInfo &arrayInfo);
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public:
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void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
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CheckBufferOverrun c(0, settings, errorLogger);
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std::vector<MathLib::bigint> indexes;
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indexes.push_back(2);
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c.arrayIndexOutOfBoundsError(0, ArrayInfo(0, "array", 1, 2), indexes);
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c.bufferOverrunError(0, std::string("buffer"));
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c.strncatUsageError(0);
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c.outOfBoundsError(0, "index", true, 2, 1);
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c.sizeArgumentAsCharError(0);
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c.terminateStrncpyError(0, "buffer");
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c.bufferNotZeroTerminatedError(0, "buffer", "strncpy");
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c.negativeIndexError(0, -1);
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c.cmdLineArgsError(0);
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c.pointerOutOfBoundsError(0, "array");
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c.arrayIndexThenCheckError(0, "index");
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c.possibleBufferOverrunError(0, "source", "destination", false);
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c.possibleReadlinkBufferOverrunError(0, "readlink", "buffer");
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c.argumentSizeError(0, "function", "array");
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c.writeOutsideBufferSizeError(0,2,3,"write");
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c.negativeMemoryAllocationSizeError(0);
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}
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private:
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static std::string myName() {
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return "Bounds checking";
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}
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std::string classInfo() const {
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return "Out of bounds checking:\n"
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"* Array index out of bounds detection by value flow analysis\n"
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"* Dangerous usage of strncat()\n"
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"* char constant passed as size to function like memset()\n"
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"* strncpy() leaving string unterminated\n"
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"* Accessing array with negative index\n"
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"* Unsafe usage of main(argv, argc) arguments\n"
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"* Accessing array with index variable before checking its value\n"
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"* Check for large enough arrays being passed to functions\n"
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"* Writing beyond bounds of a buffer\n"
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"* Allocating memory with a negative size\n";
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}
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};
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/// @}
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//---------------------------------------------------------------------------
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#endif // checkbufferoverrunH
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