558 lines
17 KiB
C++
558 lines
17 KiB
C++
/*
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* cppcheck - c/c++ syntax checking
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* Copyright (C) 2007-2008 Daniel Marjamäki, Reijo Tomperi, Nicolas Le Cam
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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 <algorithm>
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#include <sstream>
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#include <list>
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#include <cstring>
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#include <stdlib.h> // <- strtoul
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//---------------------------------------------------------------------------
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// _callStack used when parsing into subfunctions.
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CheckBufferOverrunClass::CheckBufferOverrunClass( const Tokenizer *tokenizer, const Settings &settings, ErrorLogger *errorLogger )
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: _settings(settings)
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{
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_tokenizer = tokenizer;
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_errorLogger = errorLogger;
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}
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CheckBufferOverrunClass::~CheckBufferOverrunClass()
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{
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}
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// Modified version of 'ReportError' that also reports the callstack
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void CheckBufferOverrunClass::ReportError(const TOKEN *tok, const char errmsg[])
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{
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std::ostringstream ostr;
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std::list<const TOKEN *>::const_iterator it;
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for ( it = _callStack.begin(); it != _callStack.end(); it++ )
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ostr << _tokenizer->fileLine(*it ) << " -> ";
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ostr << _tokenizer->fileLine(tok) << ": " << errmsg;
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_errorLogger->reportErr(ostr.str());
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Check array usage..
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//---------------------------------------------------------------------------
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void CheckBufferOverrunClass::CheckBufferOverrun_CheckScope( const TOKEN *tok, const char *varname[], const int size, const int total_size, unsigned int varid )
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{
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unsigned int varc = 1;
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while ( varname[varc] )
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varc++;
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varc = 2 * ( varc - 1 );
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// Array index..
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if ( varid > 0 )
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{
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if ( TOKEN::Match(tok, "%varid% [ %num% ]", 0, 0, varid) )
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{
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const char *num = tok->strAt(2);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next(), "Array index out of bounds");
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}
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}
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}
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else if ( TOKEN::Match(tok, "%var1% [ %num% ]", varname) )
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{
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const char *num = tok->strAt(2 + varc);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next(), "Array index out of bounds");
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}
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}
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int indentlevel = 0;
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for ( ; tok; tok = tok->next() )
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{
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if (tok->str() == "{")
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{
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indentlevel++;
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}
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else if (tok->str() == "}")
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{
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indentlevel--;
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if ( indentlevel < 0 )
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return;
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}
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// Array index..
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if ( varid > 0 )
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{
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if ( !tok->isName() && !TOKEN::Match(tok,"[.&]") && TOKEN::Match(tok->next(), "%varid% [ %num% ]", 0, 0, varid) )
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{
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const char *num = tok->strAt(3);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next(), "Array index out of bounds");
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}
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}
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}
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else if ( !tok->isName() && !TOKEN::Match(tok,"[.&]") && TOKEN::Match(tok->next(), "%var1% [ %num% ]", varname) )
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{
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const char *num = tok->next()->strAt(2 + varc);
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if (strtol(num, NULL, 10) >= size)
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{
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ReportError(tok->next(), "Array index out of bounds");
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}
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tok = tok->tokAt(4);
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continue;
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}
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// memset, memcmp, memcpy, strncpy, fgets..
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if ( varid > 0 )
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{
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if ( TOKEN::Match(tok, "memset|memcpy|memmove|memcmp|strncpy|fgets") )
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{
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if ( TOKEN::Match( tok->next(), "( %varid% , %num% , %num% )", 0, 0, varid ) ||
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TOKEN::Match( tok->next(), "( %var% , %varid% , %num% )", 0, 0, varid ) )
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{
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const char *num = tok->strAt(6);
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if ( atoi(num) > total_size )
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{
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ReportError(tok, "Buffer overrun");
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}
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}
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continue;
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}
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}
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else if (TOKEN::Match(tok,"memset|memcpy|memmove|memcmp|strncpy|fgets") )
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{
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if ( TOKEN::Match( tok->next(), "( %var1% , %num% , %num% )", varname ) ||
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TOKEN::Match( tok->next(), "( %var% , %var1% , %num% )", varname ) )
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{
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const char *num = tok->strAt(varc + 6);
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if ( atoi(num) > total_size )
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{
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ReportError(tok, "Buffer overrun");
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}
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}
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continue;
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}
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// Loop..
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if ( TOKEN::Match(tok, "for (") )
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{
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const TOKEN *tok2 = tok->tokAt(2);
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// for - setup..
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if ( TOKEN::Match(tok2, "%var% = 0 ;") )
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tok2 = tok2->tokAt(4);
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else if ( TOKEN::Match(tok2, "%type% %var% = 0 ;") )
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tok2 = tok2->tokAt(5);
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else if ( TOKEN::Match(tok2, "%type% %type% %var% = 0 ;") )
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tok2 = tok2->tokAt(6);
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else
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continue;
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// for - condition..
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if ( ! TOKEN::Match(tok2, "%var% < %num% ;") && ! TOKEN::Match(tok2, "%var% <= %num% ;"))
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continue;
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// Get index variable and stopsize.
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const char *strindex = tok2->aaaa();
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int value = ((tok2->next()->aaaa1() == '=') ? 1 : 0) + atoi(tok2->strAt(2));
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if ( value <= size )
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continue;
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// Goto the end of the for loop..
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while (tok2 && !TOKEN::Match(tok2,")"))
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tok2 = tok2->next();
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if (!(tok2->tokAt(5)))
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break;
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std::ostringstream pattern;
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pattern << "%var1% [ " << strindex << " ]";
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int indentlevel2 = 0;
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while (tok2)
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{
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if ( (tok2->str() == ";") && indentlevel2 == 0 )
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break;
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if ( tok2->str() == "{" )
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indentlevel2++;
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if ( tok2->str() == "}" )
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{
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indentlevel2--;
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if ( indentlevel2 <= 0 )
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break;
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}
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if ( TOKEN::Match( tok2, pattern.str().c_str(), varname ) )
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{
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ReportError(tok2, "Buffer overrun");
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break;
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}
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tok2 = tok2->next();
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}
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continue;
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}
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// Writing data into array..
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if ( TOKEN::Match(tok, "strcpy ( %var1% , %str% )", varname) )
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{
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int len = 0;
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const char *str = tok->strAt(varc + 4 );
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while ( *str )
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{
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if (*str=='\\')
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str++;
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str++;
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len++;
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}
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if (len > 2 && len >= (int)size + 2)
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{
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ReportError(tok, "Buffer overrun");
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}
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continue;
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}
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// Function call..
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// It's not interesting to check what happens when the whole struct is
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// sent as the parameter, that is checked separately anyway.
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if ( TOKEN::Match( tok, "%var% (" ) )
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{
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// Don't make recursive checking..
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if (std::find(_callStack.begin(), _callStack.end(), tok) != _callStack.end())
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continue;
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// Only perform this checking if showAll setting is enabled..
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if ( ! _settings._showAll )
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continue;
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unsigned int parlevel = 0, par = 0;
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for ( const TOKEN *tok2 = tok; tok2; tok2 = tok2->next() )
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{
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if ( tok2->str() == "(" )
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{
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parlevel++;
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}
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else if ( tok2->str() == ")" )
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{
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parlevel--;
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if ( parlevel < 1 )
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{
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par = 0;
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break;
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}
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}
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else if ( parlevel == 1 && (tok2->str() == ",") )
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{
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par++;
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}
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if ( parlevel == 1 && TOKEN::Match(tok2, "[(,] %var1% [,)]", varname) )
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{
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par++;
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break;
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}
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}
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if ( par == 0 )
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continue;
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// Find function..
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const TOKEN *ftok = _tokenizer->GetFunctionTokenByName( tok->aaaa() );
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if ( ! ftok )
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continue;
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// Parse head of function..
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ftok = ftok->tokAt(2);
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parlevel = 1;
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while ( ftok && parlevel == 1 && par >= 1 )
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{
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if ( ftok->str() == "(" )
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parlevel++;
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else if ( ftok->str() == ")" )
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parlevel--;
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else if ( ftok->str() == "," )
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par--;
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else if (par==1 && parlevel==1 && (TOKEN::Match(ftok, "%var% ,") || TOKEN::Match(ftok, "%var% )")))
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{
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// Parameter name..
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const char *parname[2];
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parname[0] = ftok->aaaa();
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parname[1] = 0;
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// Goto function body..
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while ( ftok && (ftok->str() != "{") )
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ftok = ftok->next();
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ftok = ftok ? ftok->next() : 0;
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// Check variable usage in the function..
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_callStack.push_back( tok );
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CheckBufferOverrun_CheckScope( ftok, parname, size, total_size, 0 );
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_callStack.pop_back();
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// break out..
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break;
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}
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ftok = ftok->next();
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}
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}
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}
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}
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//---------------------------------------------------------------------------
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// Checking local variables in a scope
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//---------------------------------------------------------------------------
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void CheckBufferOverrunClass::CheckBufferOverrun_LocalVariable()
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{
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int indentlevel = 0;
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for (const TOKEN *tok = _tokenizer->tokens(); tok; tok = tok->next())
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{
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if (tok->str() == "{")
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indentlevel++;
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else if (tok->str() == "}")
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indentlevel--;
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else if (indentlevel > 0)
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{
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const char *varname[2] = {0};
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unsigned int size = 0;
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const char *type = 0;
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unsigned int varid = 0;
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if (TOKEN::Match(tok, "%type% %var% [ %num% ] ;"))
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{
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varname[0] = tok->strAt(1);
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size = strtoul(tok->strAt(3), NULL, 10);
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type = tok->aaaa();
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varid = tok->tokAt(1)->varId();
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}
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else if (indentlevel > 0 && TOKEN::Match(tok, "[*;{}] %var% = new %type% [ %num% ]"))
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{
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varname[0] = tok->strAt(1);
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size = strtoul(tok->strAt(6), NULL, 10);
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type = tok->strAt(4);
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varid = tok->tokAt(1)->varId();
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}
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else
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{
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continue;
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}
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int total_size = size * _tokenizer->SizeOfType(type);
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if (total_size == 0)
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continue;
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// The callstack is empty
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_callStack.clear();
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CheckBufferOverrun_CheckScope( tok->tokAt(5), varname, size, total_size, varid );
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}
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}
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Checking member variables of structs..
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//---------------------------------------------------------------------------
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void CheckBufferOverrunClass::CheckBufferOverrun_StructVariable()
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{
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const char *declstruct_pattern[] = {"","","{",0};
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for ( const TOKEN * tok = TOKEN::findtoken( _tokenizer->tokens(), declstruct_pattern );
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tok;
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tok = TOKEN::findtoken( tok->next(), declstruct_pattern ) )
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{
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if ( ! TOKEN::Match(tok,"struct|class") )
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continue;
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const char *structname = tok->next()->aaaa();
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if ( !(tok->next()->isName()) )
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continue;
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// Found a struct declaration. Search for arrays..
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for ( const TOKEN * tok2 = tok->next()->next(); tok2; tok2 = tok2->next() )
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{
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if ( TOKEN::Match(tok2, "}") )
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break;
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int ivar = 0;
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if ( TOKEN::Match(tok2->next(), "%type% %var% [ %num% ] ;") )
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ivar = 2;
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else if ( TOKEN::Match(tok2->next(), "%type% %type% %var% [ %num% ] ;") )
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ivar = 3;
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else if ( TOKEN::Match(tok2->next(), "%type% * %var% [ %num% ] ;") )
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ivar = 3;
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else if ( TOKEN::Match(tok2->next(), "%type% %type% * %var% [ %num% ] ;") )
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ivar = 4;
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else
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continue;
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const char *varname[3] = {0,0,0};
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varname[1] = tok2->strAt(ivar);
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int arrsize = atoi(tok2->strAt(ivar+2));
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int total_size = arrsize * _tokenizer->SizeOfType(tok2->next()->aaaa());
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if (total_size == 0)
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continue;
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// Class member variable => Check functions
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if ( TOKEN::Match(tok, "class") )
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{
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std::string func_pattern(structname + std::string(" :: %var% ("));
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const TOKEN *tok3 = TOKEN::findmatch(_tokenizer->tokens(), func_pattern.c_str());
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while ( tok3 )
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{
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for ( const TOKEN *tok4 = tok3; tok4; tok4 = tok4->next() )
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{
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if ( TOKEN::Match(tok4,"[;{}]") )
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break;
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if ( TOKEN::Match(tok4, ") {") )
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{
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const char *names[2] = {varname[1], 0};
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CheckBufferOverrun_CheckScope( tok4->tokAt(2), names, arrsize, total_size, 0 );
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break;
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}
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}
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tok3 = TOKEN::findmatch(tok3->next(), func_pattern.c_str());
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}
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}
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for ( const TOKEN *tok3 = _tokenizer->tokens(); tok3; tok3 = tok3->next() )
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{
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if ( strcmp(tok3->aaaa(), structname) )
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continue;
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// Declare variable: Fred fred1;
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if ( TOKEN::Match( tok3->next(), "%var% ;" ) )
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varname[0] = tok3->strAt(1);
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// Declare pointer: Fred *fred1
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else if ( TOKEN::Match(tok3->next(), "* %var% [,);=]") )
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varname[0] = tok3->strAt(2);
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else
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continue;
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// Goto end of statement.
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const TOKEN *CheckTok = NULL;
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while ( tok3 )
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{
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// End of statement.
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if ( TOKEN::Match(tok3, ";") )
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{
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CheckTok = tok3;
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break;
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}
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// End of function declaration..
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if ( TOKEN::Match(tok3, ") ;") )
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break;
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// Function implementation..
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if ( TOKEN::Match(tok3, ") {") )
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{
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CheckTok = tok3->tokAt(2);
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break;
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}
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tok3 = tok3->next();
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}
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if ( ! tok3 )
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break;
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if ( ! CheckTok )
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continue;
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// Check variable usage..
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CheckBufferOverrun_CheckScope( CheckTok, varname, arrsize, total_size, 0 );
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}
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}
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}
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}
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//---------------------------------------------------------------------------
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void CheckBufferOverrunClass::bufferOverrun()
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{
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CheckBufferOverrun_LocalVariable();
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CheckBufferOverrun_StructVariable();
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}
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//---------------------------------------------------------------------------
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//---------------------------------------------------------------------------
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// Dangerous functions
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//---------------------------------------------------------------------------
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void CheckBufferOverrunClass::dangerousFunctions()
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{
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for (const TOKEN *tok = _tokenizer->tokens(); tok; tok = tok->next())
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{
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if (TOKEN::Match(tok, "gets|scanf ("))
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{
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std::ostringstream ostr;
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ostr << _tokenizer->fileLine(tok) << ": Found '" << tok->str() << "'. You should use 'fgets' instead";
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_errorLogger->reportErr(ostr.str());
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}
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}
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}
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//---------------------------------------------------------------------------
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