cppcheck/lib/checkbufferoverrun.h

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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.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
#ifndef checkbufferoverrunH
#define checkbufferoverrunH
//---------------------------------------------------------------------------
#include "config.h"
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#include "check.h"
#include "mathlib.h"
#include <list>
#include <vector>
#include <string>
class Variable;
/// @addtogroup Checks
/// @{
/**
* @brief buffer overruns and array index out of bounds
*
* Buffer overrun and array index out of bounds are pretty much the same.
* But I generally use 'array index' if the code contains []. And the given
* index is out of bounds.
* I generally use 'buffer overrun' if you for example call a strcpy or
* other function and pass a buffer and reads or writes too much data.
*/
class CPPCHECKLIB CheckBufferOverrun : public Check {
public:
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/** This constructor is used when registering the CheckClass */
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CheckBufferOverrun() : Check(myName()) {
}
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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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void runSimplifiedChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) {
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CheckBufferOverrun checkBufferOverrun(tokenizer, settings, errorLogger);
checkBufferOverrun.bufferOverrun();
checkBufferOverrun.bufferOverrun2();
checkBufferOverrun.arrayIndexThenCheck();
checkBufferOverrun.writeOutsideBufferSize();
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}
/** @brief %Check for buffer overruns */
void bufferOverrun();
/** @brief %Check for buffer overruns #2 (single pass, use ast and valueflow) */
void bufferOverrun2();
/** @brief Using array index before bounds check */
void arrayIndexThenCheck();
/** @brief %Check for buffer overruns by inspecting execution paths */
void executionPaths();
/** @brief %Check using POSIX write function and writing outside buffer size */
void writeOutsideBufferSize();
/**
* @brief Get minimum length of format string result
* @param input_string format string
* @param parameters given parameters to sprintf
* @return minimum length of resulting string
*/
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static MathLib::bigint countSprintfLength(const std::string &input_string, const std::list<const Token*> &parameters);
/**
* @brief %Check code that matches: "sprintf ( %varid% , %str% [,)]" when varid is not 0,
* and report found errors.
* @param tok The "sprintf" token.
* @param size The size of the buffer where sprintf is writing.
*/
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void checkSprintfCall(const Token *tok, const MathLib::bigint size);
/** Check for buffer overruns - locate struct variables and check them with the .._CheckScope function */
void checkStructVariable();
/** Check for buffer overruns - locate global variables and local function variables and check them with the checkScope function */
void checkGlobalAndLocalVariable();
/** Check for buffer overruns due to allocating strlen(src) bytes instead of (strlen(src)+1) bytes before copying a string */
void checkBufferAllocatedWithStrlen();
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/** Check string argument buffer overruns */
void checkStringArgument();
/** Check for buffer overruns due to copying command-line args to fixed-sized buffers without bounds checking */
void checkInsecureCmdLineArgs();
/** Information about N-dimensional array */
class CPPCHECKLIB ArrayInfo {
private:
/** number of elements of array */
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std::vector<MathLib::bigint> _num;
/** full name of variable as pattern */
std::string _varname;
/** size of each element in array */
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MathLib::bigint _element_size;
/** declaration id */
unsigned int _declarationId;
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public:
ArrayInfo();
ArrayInfo(const Variable *var, const Tokenizer *tokenizer, const unsigned int forcedeclid = 0);
/**
* 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.
*/
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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 */
ArrayInfo limit(MathLib::bigint value) const;
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/** array sizes */
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const std::vector<MathLib::bigint> &num() const {
return _num;
}
/** array size */
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MathLib::bigint num(std::size_t index) const {
return _num[index];
}
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void num(std::size_t index, MathLib::bigint number) {
_num[index] = number;
}
/** size of each element */
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MathLib::bigint element_size() const {
return _element_size;
}
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/** Variable name */
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unsigned int declarationId() const {
return _declarationId;
}
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void declarationId(unsigned int id) {
_declarationId = id;
}
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/** Variable name */
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const std::string &varname() const {
return _varname;
}
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void varname(const std::string &name) {
_varname = name;
}
};
/** Check for buffer overruns (based on ArrayInfo) */
void checkScope(const Token *tok, const ArrayInfo &arrayInfo);
/** Check for buffer overruns */
void checkScope(const Token *tok, const std::vector<std::string> &varname, const ArrayInfo &arrayInfo);
/** Check readlink or readlinkat() buffer usage */
void checkReadlinkBufferUsage(const Token *ftok, const Token *scope_begin, const unsigned int varid, const MathLib::bigint total_size);
/**
* Helper function for checkFunctionCall - check a function parameter
* \param tok token for the function name
* \param par on what parameter is the array used
* \param arrayInfo the array information
* \param callstack call stack. This is used to prevent recursion and to provide better error messages. Pass a empty list from checkScope etc.
*/
void checkFunctionParameter(const Token &tok, const unsigned int par, const ArrayInfo &arrayInfo, const std::list<const Token *>& callstack);
/**
* Helper function that checks if the array is used and if so calls the checkFunctionCall
* @param tok token that matches "%var% ("
* @param arrayInfo the array information
* \param callstack call stack. This is used to prevent recursion and to provide better error messages. Pass a empty list from checkScope etc.
*/
void checkFunctionCall(const Token *tok, const ArrayInfo &arrayInfo, std::list<const Token *> callstack);
void arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index);
void arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<ValueFlow::Value> &index);
/* data for multifile checking */
class MyFileInfo : public Check::FileInfo {
public:
struct ArrayUsage {
MathLib::bigint index;
std::string fileName;
unsigned int linenr;
};
/* key:arrayName */
std::map<std::string, struct ArrayUsage> arrayUsage;
/* key:arrayName, data:arraySize */
std::map<std::string, MathLib::bigint> arraySize;
};
/** @brief Parse current TU and extract file info */
Check::FileInfo *getFileInfo(const Tokenizer *tokenizer, const Settings *settings) const;
/** @brief Analyse all file infos for all TU */
void analyseWholeProgram(const std::list<Check::FileInfo*> &fileInfo, ErrorLogger &errorLogger);
private:
static bool isArrayOfStruct(const Token* tok, int &position);
void arrayIndexOutOfBoundsError(const std::list<const Token *> &callstack, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index);
void bufferOverrunError(const Token *tok, const std::string &varnames = emptyString);
void bufferOverrunError(const std::list<const Token *> &callstack, const std::string &varnames = emptyString);
void strncatUsageError(const Token *tok);
void negativeMemoryAllocationSizeError(const Token *tok); // provide a negative value to memory allocation function
void outOfBoundsError(const Token *tok, const std::string &what, const bool show_size_info, const MathLib::bigint &supplied_size, const MathLib::bigint &actual_size);
void sizeArgumentAsCharError(const Token *tok);
void terminateStrncpyError(const Token *tok, const std::string &varname);
void bufferNotZeroTerminatedError(const Token *tok, const std::string &varname, const std::string &function);
void negativeIndexError(const Token *tok, MathLib::bigint index);
void negativeIndexError(const Token *tok, const ValueFlow::Value &index);
void cmdLineArgsError(const Token *tok);
void pointerOutOfBoundsError(const Token *tok, const std::string &object); // UB when result of calculation is out of bounds
void arrayIndexThenCheckError(const Token *tok, const std::string &indexName);
void possibleBufferOverrunError(const Token *tok, const std::string &src, const std::string &dst, bool cat);
void possibleReadlinkBufferOverrunError(const Token *tok, const std::string &funcname, const std::string &varname);
void argumentSizeError(const Token *tok, const std::string &functionName, const std::string &varname);
void writeOutsideBufferSizeError(const Token *tok, const std::size_t stringLength, const MathLib::bigint writeLength, const std::string& functionName);
void valueFlowCheckArrayIndex(const Token * const tok, const ArrayInfo &arrayInfo);
public:
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void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
CheckBufferOverrun c(0, settings, errorLogger);
std::vector<MathLib::bigint> indexes;
indexes.push_back(2);
c.arrayIndexOutOfBoundsError(0, ArrayInfo(0, "array", 1, 2), indexes);
c.bufferOverrunError(0, std::string("buffer"));
c.strncatUsageError(0);
c.outOfBoundsError(0, "index", true, 2, 1);
c.sizeArgumentAsCharError(0);
c.terminateStrncpyError(0, "buffer");
c.bufferNotZeroTerminatedError(0, "buffer", "strncpy");
c.negativeIndexError(0, -1);
c.cmdLineArgsError(0);
c.pointerOutOfBoundsError(0, "array");
c.arrayIndexThenCheckError(0, "index");
c.possibleBufferOverrunError(0, "source", "destination", false);
c.possibleReadlinkBufferOverrunError(0, "readlink", "buffer");
c.argumentSizeError(0, "function", "array");
c.writeOutsideBufferSizeError(0,2,3,"write");
c.negativeMemoryAllocationSizeError(0);
c.reportError(nullptr, Severity::warning, "arrayIndexOutOfBoundsCond", "Array 'x[10]' accessed at index 20, which is out of bounds. Otherwise condition 'y==20' is redundant.");
}
private:
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static std::string myName() {
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return "Bounds checking";
}
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std::string classInfo() const {
return "Out of bounds checking:\n"
"- Array index out of bounds detection by value flow analysis\n"
"- Dangerous usage of strncat()\n"
"- char constant passed as size to function like memset()\n"
"- strncpy() leaving string unterminated\n"
"- Accessing array with negative index\n"
"- Unsafe usage of main(argv, argc) arguments\n"
"- Accessing array with index variable before checking its value\n"
"- Check for large enough arrays being passed to functions\n"
"- Writing beyond bounds of a buffer\n"
"- Allocating memory with a negative size\n";
}
};
/// @}
//---------------------------------------------------------------------------
#endif // checkbufferoverrunH