cppcheck/lib/checkbufferoverrun.h

/*
 * Cppcheck - A tool for static C/C++ code analysis
 * Copyright (C) 2007-2019 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 "check.h"
#include "config.h"
#include "errorlogger.h"
#include "mathlib.h"
#include "tokenize.h"

#include <cstddef>
#include <list>
#include <map>
#include <string>
#include <vector>


/// @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:

    /** This constructor is used when registering the CheckClass */
    CheckBufferOverrun() : Check(myName()) {
    }

    /** This constructor is used when running checks. */
    CheckBufferOverrun(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger)
        : Check(myName(), tokenizer, settings, errorLogger) {
    }

    void runChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) OVERRIDE {
        CheckBufferOverrun checkBufferOverrun(tokenizer, settings, errorLogger);
        checkBufferOverrun.arrayIndex();
        checkBufferOverrun.bufferOverflow();
        checkBufferOverrun.arrayIndexThenCheck();
        checkBufferOverrun.stringNotZeroTerminated();
    }

    void runSimplifiedChecks(const Tokenizer *tokenizer, const Settings *settings, ErrorLogger *errorLogger) OVERRIDE {
        (void)tokenizer;
        (void)settings;
        (void)errorLogger;
    }

    void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const OVERRIDE {
        CheckBufferOverrun c(nullptr, settings, errorLogger);
        c.arrayIndexError(nullptr, nullptr, nullptr);
        c.negativeIndexError(nullptr, nullptr, nullptr);
        c.arrayIndexThenCheckError(nullptr, "i");
    }

private:

    void arrayIndex();
    void arrayIndexError(const Token *tok, const Variable *var, const ValueFlow::Value *index);
    void negativeIndexError(const Token *tok, const Variable *var, const ValueFlow::Value *negativeValue);

    void bufferOverflow();
    void bufferOverflowError(const Token *tok);

    void arrayIndexThenCheck();
    void arrayIndexThenCheckError(const Token *tok, const std::string &indexName);

    void stringNotZeroTerminated();
    void terminateStrncpyError(const Token *tok, const std::string &varname);
    void bufferNotZeroTerminatedError(const Token *tok, const std::string &varname, const std::string &function);


    size_t getBufferSize(const Token *bufTok) const;

    static std::string myName() {
        return "Bounds checking";
    }

    std::string classInfo() const OVERRIDE {
        return "Out of bounds checking:\n"
               "- Array index out of bounds\n"
               "- Buffer overflow\n"
               "- Dangerous usage of strncat()\n"
               "- Using array index before checking it\n"
               "- Partial string write that leads to buffer that is not zero terminated.\n";
    }
};
/// @}
//---------------------------------------------------------------------------
#endif // checkbufferoverrunH