/* * Cppcheck - A tool for static C/C++ code analysis * Copyright (C) 2007-2018 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 . */ #include "checkstl.h" #include "checknullpointer.h" #include "errorlogger.h" #include "settings.h" #include "standards.h" #include "symboldatabase.h" #include "token.h" #include "utils.h" #include "astutils.h" #include #include #include #include #include // Register this check class (by creating a static instance of it) namespace { CheckStl instance; } // CWE IDs used: static const struct CWE CWE398(398U); // Indicator of Poor Code Quality static const struct CWE CWE597(597U); // Use of Wrong Operator in String Comparison static const struct CWE CWE628(628U); // Function Call with Incorrectly Specified Arguments static const struct CWE CWE664(664U); // Improper Control of a Resource Through its Lifetime static const struct CWE CWE704(704U); // Incorrect Type Conversion or Cast static const struct CWE CWE762(762U); // Mismatched Memory Management Routines static const struct CWE CWE786(786U); // Access of Memory Location Before Start of Buffer static const struct CWE CWE788(788U); // Access of Memory Location After End of Buffer static const struct CWE CWE825(825U); // Expired Pointer Dereference static const struct CWE CWE834(834U); // Excessive Iteration void CheckStl::outOfBounds() { for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) { for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) { if (!tok->isName() || !tok->valueType()) continue; const Library::Container *container = tok->valueType()->container; if (!container) continue; for (const ValueFlow::Value &value : tok->values()) { if (!value.isContainerSizeValue()) continue; if (value.isInconclusive() && !mSettings->inconclusive) continue; if (!value.errorSeverity() && !mSettings->isEnabled(Settings::WARNING)) continue; if (value.intvalue == 0 && Token::Match(tok, "%name% . %name% (") && container->getYield(tok->strAt(2)) == Library::Container::Yield::ITEM) { outOfBoundsError(tok, &value, nullptr); continue; } if (!container->arrayLike_indexOp && !container->stdStringLike) continue; if (value.intvalue == 0 && Token::Match(tok, "%name% [")) { outOfBoundsError(tok, &value, nullptr); continue; } if (container->arrayLike_indexOp && Token::Match(tok, "%name% [")) { const ValueFlow::Value *indexValue = tok->next()->astOperand2() ? tok->next()->astOperand2()->getMaxValue(false) : nullptr; if (indexValue && indexValue->intvalue >= value.intvalue) { outOfBoundsError(tok, &value, indexValue); continue; } if (mSettings->isEnabled(Settings::WARNING)) { indexValue = tok->next()->astOperand2() ? tok->next()->astOperand2()->getMaxValue(true) : nullptr; if (indexValue && indexValue->intvalue >= value.intvalue) { outOfBoundsError(tok, &value, indexValue); continue; } } } } } } } void CheckStl::outOfBoundsError(const Token *tok, const ValueFlow::Value *containerSize, const ValueFlow::Value *index) { // Do not warn if both the container size and index are possible if (containerSize && index && containerSize->isPossible() && index->isPossible()) return; const std::string varname = tok ? tok->str() : std::string("var"); std::string errmsg; if (!containerSize) errmsg = "Out of bounds access of item in container '$symbol'"; else if (containerSize->intvalue == 0) { if (containerSize->condition) errmsg = "Accessing an item in container '$symbol'. " + ValueFlow::eitherTheConditionIsRedundant(containerSize->condition) + " or '$symbol' can be empty."; else errmsg = "Accessing an item in container '$symbol' that is empty."; } else if (index) { if (containerSize->condition || index->condition) errmsg = "Possible access out of bounds"; else errmsg = "Access out of bounds"; errmsg += " of container '$symbol'; size=" + MathLib::toString(containerSize->intvalue) + ", index=" + MathLib::toString(index->intvalue); } else { // should not happen return; } ErrorPath errorPath; if (!index) errorPath = getErrorPath(tok, containerSize, "Access out of bounds"); else { ErrorPath errorPath1 = getErrorPath(tok, containerSize, "Access out of bounds"); ErrorPath errorPath2 = getErrorPath(tok, index, "Access out of bounds"); if (errorPath1.size() <= 1) errorPath = errorPath2; else if (errorPath2.size() <= 1) errorPath = errorPath1; else { errorPath = errorPath1; errorPath.splice(errorPath.end(), errorPath2); } } reportError(errorPath, (containerSize && !containerSize->errorSeverity()) || (index && !index->errorSeverity()) ? Severity::warning : Severity::error, "containerOutOfBounds", "$symbol:" + varname +"\n" + errmsg, CWE398, (containerSize && containerSize->isInconclusive()) || (index && index->isInconclusive())); } // Error message for bad iterator usage.. void CheckStl::invalidIteratorError(const Token *tok, const std::string &iteratorName) { reportError(tok, Severity::error, "invalidIterator1", "$symbol:"+iteratorName+"\nInvalid iterator: $symbol", CWE664, false); } void CheckStl::iteratorsError(const Token *tok, const std::string &container1, const std::string &container2) { reportError(tok, Severity::error, "iterators", "$symbol:" + container1 + "\n" "$symbol:" + container2 + "\n" "Same iterator is used with different containers '" + container1 + "' and '" + container2 + "'.", CWE664, false); } // Error message used when dereferencing an iterator that has been erased.. void CheckStl::dereferenceErasedError(const Token *erased, const Token* deref, const std::string &itername, bool inconclusive) { if (erased) { std::list callstack = { deref, erased }; reportError(callstack, Severity::error, "eraseDereference", "$symbol:" + itername + "\n" "Iterator '$symbol' used after element has been erased.\n" "The iterator '$symbol' is invalid after the element it pointed to has been erased. " "Dereferencing or comparing it with another iterator is invalid operation.", CWE664, inconclusive); } else { reportError(deref, Severity::error, "eraseDereference", "$symbol:" + itername + "\n" "Invalid iterator '$symbol' used.\n" "The iterator '$symbol' is invalid before being assigned. " "Dereferencing or comparing it with another iterator is invalid operation.", CWE664, inconclusive); } } static const Token *skipMembers(const Token *tok) { while (Token::Match(tok, "%name% .")) tok = tok->tokAt(2); return tok; } static bool isIterator(const Variable *var, bool& inconclusiveType) { // Check that its an iterator if (!var || !var->isLocal() || !Token::Match(var->typeEndToken(), "iterator|const_iterator|reverse_iterator|const_reverse_iterator|auto")) return false; inconclusiveType = false; if (var->typeEndToken()->str() == "auto") return (var->nameToken()->valueType() && var->nameToken()->valueType()->type == ValueType::Type::ITERATOR); if (var->type()) { // If it is defined, ensure that it is defined like an iterator // look for operator* and operator++ const Function* end = var->type()->getFunction("operator*"); const Function* incOperator = var->type()->getFunction("operator++"); if (!end || end->argCount() > 0 || !incOperator) { return false; } else { inconclusiveType = true; // heuristics only } } return true; } static std::string getContainerName(const Token *containerToken) { if (!containerToken) return std::string(); std::string ret(containerToken->str()); for (const Token *nametok = containerToken; nametok; nametok = nametok->tokAt(-2)) { if (!Token::Match(nametok->tokAt(-2), "%name% .")) break; ret = nametok->strAt(-2) + '.' + ret; } return ret; } void CheckStl::iterators() { const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable* var : symbolDatabase->variableList()) { bool inconclusiveType=false; if (!isIterator(var, inconclusiveType)) continue; const unsigned int iteratorId = var->declarationId(); // the validIterator flag says if the iterator has a valid value or not bool validIterator = Token::Match(var->nameToken()->next(), "[(=:{]"); const Scope* invalidationScope = nullptr; // The container this iterator can be used with const Token* containerToken = nullptr; const Scope* containerAssignScope = nullptr; // When "validatingToken" is reached the validIterator is set to true const Token* validatingToken = nullptr; const Token* eraseToken = nullptr; // Scan through the rest of the code and see if the iterator is // used against other containers. for (const Token *tok2 = var->nameToken(); tok2 && tok2 != var->scope()->bodyEnd; tok2 = tok2->next()) { if (invalidationScope && tok2 == invalidationScope->bodyEnd) validIterator = true; // Assume that the iterator becomes valid again if (containerAssignScope && tok2 == containerAssignScope->bodyEnd) containerToken = nullptr; // We don't know which containers might be used with the iterator if (tok2 == validatingToken) { validIterator = true; eraseToken = nullptr; invalidationScope = nullptr; } // Is iterator compared against different container? if (tok2->isComparisonOp() && containerToken && tok2->astOperand1() && tok2->astOperand2()) { const Token *other = nullptr; if (tok2->astOperand1()->varId() == iteratorId) other = tok2->astOperand2()->tokAt(-3); else if (tok2->astOperand2()->varId() == iteratorId) other = tok2->astOperand1()->tokAt(-3); if (Token::Match(other, "%name% . end|rend|cend|crend ( )") && other->varId() != containerToken->varId()) iteratorsError(tok2, getContainerName(containerToken), getContainerName(other)); } // Is the iterator used in a insert/erase operation? else if (Token::Match(tok2, "%name% . insert|erase ( *| %varid% )|,", iteratorId)) { const Token* itTok = tok2->tokAt(4); if (itTok->str() == "*") { if (tok2->strAt(2) == "insert") continue; itTok = itTok->next(); } // It is bad to insert/erase an invalid iterator if (!validIterator) invalidIteratorError(tok2, itTok->str()); // If insert/erase is used on different container then // report an error if (containerToken && tok2->varId() != containerToken->varId()) { // skip error message if container is a set.. const Variable *variableInfo = tok2->variable(); const Token *decltok = variableInfo ? variableInfo->typeStartToken() : nullptr; if (Token::simpleMatch(decltok, "std :: set")) continue; // No warning // skip error message if the iterator is erased/inserted by value if (itTok->previous()->str() == "*") continue; // inserting iterator range.. if (tok2->strAt(2) == "insert") { const Token *par2 = itTok->nextArgument(); if (!par2 || par2->nextArgument()) continue; while (par2->str() != ")") { if (par2->varId() == containerToken->varId()) break; bool inconclusiveType2=false; if (isIterator(par2->variable(), inconclusiveType2)) break; // TODO: check if iterator points at same container if (par2->str() == "(") par2 = par2->link(); par2 = par2->next(); } if (par2->str() != ")") continue; } // Show error message, mismatching iterator is used. iteratorsError(tok2, getContainerName(containerToken), getContainerName(tok2)); } // invalidate the iterator if it is erased else if (tok2->strAt(2) == "erase" && (tok2->strAt(4) != "*" || (containerToken && tok2->varId() == containerToken->varId()))) { validIterator = false; eraseToken = tok2; invalidationScope = tok2->scope(); } // skip the operation tok2 = itTok->next(); } // it = foo.erase(.. // taking the result of an erase is ok else if (Token::Match(tok2, "%varid% = %name% .", iteratorId) && Token::simpleMatch(skipMembers(tok2->tokAt(2)), "erase (")) { // the returned iterator is valid validatingToken = skipMembers(tok2->tokAt(2))->linkAt(1); tok2 = validatingToken->link(); } // Reassign the iterator else if (Token::Match(tok2, "%varid% = %name% .", iteratorId) && Token::Match(skipMembers(tok2->tokAt(2)), "begin|rbegin|cbegin|crbegin|find (")) { validatingToken = skipMembers(tok2->tokAt(2))->linkAt(1); containerToken = skipMembers(tok2->tokAt(2))->tokAt(-2); if (containerToken->varId() == 0 || Token::simpleMatch(validatingToken, ") .")) containerToken = nullptr; containerAssignScope = tok2->scope(); // skip ahead tok2 = validatingToken->link(); } // Reassign the iterator else if (Token::Match(tok2, "%varid% =", iteratorId)) { // Assume that the iterator becomes valid. // TODO: add checking that checks if the iterator becomes valid or not validatingToken = Token::findmatch(tok2->tokAt(2), "[;)]"); // skip ahead tok2 = tok2->tokAt(2); } // Passing iterator to function. Iterator might be initialized else if (Token::Match(tok2, "%varid% ,|)", iteratorId)) { validIterator = true; } // Dereferencing invalid iterator? else if (!validIterator && Token::Match(tok2, "* %varid%", iteratorId)) { dereferenceErasedError(eraseToken, tok2, tok2->strAt(1), inconclusiveType); tok2 = tok2->next(); } else if (!validIterator && Token::Match(tok2, "%varid% . %name%", iteratorId)) { dereferenceErasedError(eraseToken, tok2, tok2->str(), inconclusiveType); tok2 = tok2->tokAt(2); } // bailout handling. Assume that the iterator becomes valid if we see return/break. // TODO: better handling else if (tok2->scope() == invalidationScope && Token::Match(tok2, "return|break|continue")) { validatingToken = Token::findsimplematch(tok2->next(), ";"); } // bailout handling. Assume that the iterator becomes valid if we see else. // TODO: better handling else if (tok2->str() == "else") { validIterator = true; } } } } // Error message for bad iterator usage.. void CheckStl::mismatchingContainersError(const Token *tok) { reportError(tok, Severity::error, "mismatchingContainers", "Iterators of different containers are used together.", CWE664, false); } void CheckStl::mismatchingContainerExpressionError(const Token *tok1, const Token *tok2) { const std::string expr1(tok1 ? tok1->expressionString() : std::string("v1")); const std::string expr2(tok2 ? tok2->expressionString() : std::string("v2")); reportError(tok1, Severity::warning, "mismatchingContainerExpression", "Iterators to containers from different expressions '" + expr1 + "' and '" + expr2 + "' are used together.", CWE664, false); } void CheckStl::sameIteratorExpressionError(const Token *tok) { reportError(tok, Severity::style, "sameIteratorExpression", "Same iterators expression are used for algorithm.", CWE664, false); } static const std::set algorithm2 = { // func(begin1, end1 "binary_search", "copy", "copy_if", "equal_range" , "generate", "is_heap", "is_heap_until", "is_partitioned" , "is_permutation", "is_sorted", "is_sorted_until", "lower_bound", "make_heap", "max_element", "minmax_element" , "min_element", "mismatch", "move", "move_backward", "next_permutation", "partition", "partition_copy" , "partition_point", "pop_heap", "prev_permutation", "push_heap", "random_shuffle", "remove", "remove_copy" , "remove_copy_if", "remove_if", "replace", "replace_copy", "replace_copy_if", "replace_if", "reverse", "reverse_copy" , "shuffle", "sort", "sort_heap", "stable_partition", "stable_sort", "swap_ranges", "transform", "unique" , "unique_copy", "upper_bound", "string", "wstring", "u16string", "u32string" }; static const std::set algorithm22 = { // func(begin1, end1, begin2, end2 "includes", "lexicographical_compare", "merge", "partial_sort_copy" , "set_difference", "set_intersection", "set_symmetric_difference", "set_union" }; static const std::set algorithm1x1 = { // func(begin1, x, end1 "nth_element", "partial_sort", "rotate", "rotate_copy" }; static const std::string iteratorBeginFuncPattern = "begin|cbegin|rbegin|crbegin"; static const std::string iteratorEndFuncPattern = "end|cend|rend|crend"; static const std::string pattern1x1_1 = "%name% . " + iteratorBeginFuncPattern + " ( ) , "; static const std::string pattern1x1_2 = "%name% . " + iteratorEndFuncPattern + " ( ) ,|)"; static const std::string pattern2 = pattern1x1_1 + pattern1x1_2; static const Variable *getContainer(const Token *argtok) { while (argtok && argtok->astOperand1()) argtok = argtok->astOperand1(); if (!Token::Match(argtok, "%var% . begin|end|rbegin|rend ( )")) // TODO: use Library yield return nullptr; const Variable *var = argtok->variable(); if (var && Token::simpleMatch(var->typeStartToken(), "std ::")) return var; return nullptr; } static const Token * getIteratorExpression(const Token * tok) { if (!tok) return nullptr; if (!tok->isName()) { const Token *iter1 = getIteratorExpression(tok->astOperand1()); if (iter1) return iter1; if (tok->str() == "(") return nullptr; const Token *iter2 = getIteratorExpression(tok->astOperand2()); if (iter2) return iter2; } else if (Token::Match(tok, "begin|cbegin|rbegin|crbegin|end|cend|rend|crend (")) { if (Token::Match(tok->previous(), ". %name% ( )")) return tok->previous()->astOperand1(); if (Token::Match(tok, "%name% ( !!)")) return tok->next()->astOperand2(); } return nullptr; } void CheckStl::mismatchingContainers() { // Check if different containers are used in various calls of standard functions const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "%comp%|-")) { const Token * iter1 = getIteratorExpression(tok->astOperand1()); const Token * iter2 = getIteratorExpression(tok->astOperand2()); if (iter1 && iter2 && !isSameExpression(true, false, iter1, iter2, mSettings->library, false)) { mismatchingContainerExpressionError(iter1, iter2); continue; } } if (!Token::Match(tok, "%name% ( !!)")) continue; const Token * const ftok = tok; const Token * firstArg = nullptr; const std::vector args = getArguments(ftok); if (args.size() < 2) continue; std::map containerNr; for (unsigned int argnr = 1; argnr <= args.size(); ++argnr) { const Library::ArgumentChecks::IteratorInfo *i = mSettings->library.getArgIteratorInfo(ftok, argnr); if (!i) continue; const Token * const argTok = args[argnr - 1]; if (i->first) { firstArg = argTok; } if (i->last && firstArg && argTok && isSameExpression(true, false, firstArg, argTok, mSettings->library, false)) { sameIteratorExpressionError(firstArg); } const Variable *c = getContainer(argTok); if (c) { std::map::const_iterator it = containerNr.find(c); if (it == containerNr.end()) { for (it = containerNr.begin(); it != containerNr.end(); ++it) { if (it->second == i->container) { mismatchingContainersError(argTok); break; } } containerNr[c] = i->container; } else if (it->second != i->container) { mismatchingContainersError(argTok); } } else { if (i->last && firstArg && argTok) { const Token * iter1 = getIteratorExpression(firstArg); const Token * iter2 = getIteratorExpression(argTok); if (iter1 && iter2 && !isSameExpression(true, false, iter1, iter2, mSettings->library, false)) { mismatchingContainerExpressionError(iter1, iter2); } } } } const int ret = mSettings->library.returnValueContainer(ftok); if (ret != -1 && Token::Match(ftok->next()->astParent(), "==|!=")) { const Token *parent = ftok->next()->astParent(); const Token *other = (parent->astOperand1() == ftok->next()) ? parent->astOperand2() : parent->astOperand1(); const Variable *c = getContainer(other); if (c) { const std::map::const_iterator it = containerNr.find(c); if (it == containerNr.end() || it->second != ret) mismatchingContainersError(other); } } } } for (const Variable *var : symbolDatabase->variableList()) { if (var && var->isStlStringType() && Token::Match(var->nameToken(), "%var% (") && Token::Match(var->nameToken()->tokAt(2), pattern2.c_str())) { if (var->nameToken()->strAt(2) != var->nameToken()->strAt(8)) { mismatchingContainersError(var->nameToken()); } } } } void CheckStl::stlOutOfBounds() { const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); // Scan through all scopes.. for (const Scope &scope : symbolDatabase->scopeList) { const Token* tok = scope.classDef; // only interested in conditions if ((scope.type != Scope::eFor && scope.type != Scope::eWhile && scope.type != Scope::eIf && scope.type != Scope::eDo) || !tok) continue; if (scope.type == Scope::eFor) tok = Token::findsimplematch(tok->tokAt(2), ";"); else if (scope.type == Scope::eDo) { tok = tok->linkAt(1)->tokAt(2); } else tok = tok->next(); if (!tok) continue; tok = tok->next(); // check if the for loop condition is wrong if (!Token::Match(tok, "%var% <= %var% . %name% ( ) ;|)|%oror%")) continue; // Is it a vector? const Variable *var = tok->tokAt(2)->variable(); if (!var) continue; const Library::Container* container = mSettings->library.detectContainer(var->typeStartToken()); if (!container) continue; if (container->getYield(tok->strAt(4)) != Library::Container::SIZE) continue; // variable id for loop variable. const unsigned int numId = tok->varId(); // variable id for the container variable const unsigned int declarationId = var->declarationId(); for (const Token *tok3 = scope.bodyStart; tok3 && tok3 != scope.bodyEnd; tok3 = tok3->next()) { if (tok3->varId() == declarationId) { tok3 = tok3->next(); if (Token::Match(tok3, ". %name% ( )")) { if (container->getYield(tok3->strAt(1)) == Library::Container::SIZE) break; } else if (container->arrayLike_indexOp && Token::Match(tok3, "[ %varid% ]", numId)) stlOutOfBoundsError(tok3, tok3->strAt(1), var->name(), false); else if (Token::Match(tok3, ". %name% ( %varid% )", numId)) { const Library::Container::Yield yield = container->getYield(tok3->strAt(1)); if (yield == Library::Container::AT_INDEX) stlOutOfBoundsError(tok3, tok3->strAt(3), var->name(), true); } } } } } void CheckStl::stlOutOfBoundsError(const Token *tok, const std::string &num, const std::string &var, bool at) { if (at) reportError(tok, Severity::error, "stlOutOfBounds", "$symbol:" + var + "\nWhen " + num + "==$symbol.size(), $symbol.at(" + num + ") is out of bounds.", CWE788, false); else reportError(tok, Severity::error, "stlOutOfBounds", "$symbol:" + var + "\nWhen " + num + "==$symbol.size(), $symbol[" + num + "] is out of bounds.", CWE788, false); } void CheckStl::negativeIndex() { // Negative index is out of bounds.. const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (!Token::Match(tok, "%var% [") || WRONG_DATA(!tok->next()->astOperand2(), tok)) continue; const Variable * const var = tok->variable(); if (!var || tok == var->nameToken()) continue; const Library::Container * const container = mSettings->library.detectContainer(var->typeStartToken()); if (!container || !container->arrayLike_indexOp) continue; const ValueFlow::Value *index = tok->next()->astOperand2()->getValueLE(-1, mSettings); if (!index) continue; negativeIndexError(tok, *index); } } } void CheckStl::negativeIndexError(const Token *tok, const ValueFlow::Value &index) { const ErrorPath errorPath = getErrorPath(tok, &index, "Negative array index"); std::ostringstream errmsg; if (index.condition) errmsg << ValueFlow::eitherTheConditionIsRedundant(index.condition) << ", otherwise there is negative array index " << index.intvalue << "."; else errmsg << "Array index " << index.intvalue << " is out of bounds."; reportError(errorPath, index.errorSeverity() ? Severity::error : Severity::warning, "negativeContainerIndex", errmsg.str(), CWE786, index.isInconclusive()); } void CheckStl::erase() { const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope &scope : symbolDatabase->scopeList) { if (scope.type == Scope::eFor && Token::simpleMatch(scope.classDef, "for (")) { const Token *tok = scope.classDef->linkAt(1); if (!Token::Match(tok->tokAt(-3), "; ++| %var% ++| ) {")) continue; tok = tok->previous(); if (!tok->isName()) tok = tok->previous(); eraseCheckLoopVar(scope, tok->variable()); } else if (scope.type == Scope::eWhile && Token::Match(scope.classDef, "while ( %var% !=")) { eraseCheckLoopVar(scope, scope.classDef->tokAt(2)->variable()); } } } void CheckStl::eraseCheckLoopVar(const Scope &scope, const Variable *var) { bool inconclusiveType=false; if (!isIterator(var, inconclusiveType)) return; for (const Token *tok = scope.bodyStart; tok != scope.bodyEnd; tok = tok->next()) { if (tok->str() != "(") continue; if (!Token::Match(tok->tokAt(-2), ". erase ( ++| %varid% )", var->declarationId())) continue; if (Token::simpleMatch(tok->astParent(), "=")) continue; // Iterator is invalid.. unsigned int indentlevel = 0U; const Token *tok2 = tok->link(); for (; tok2 != scope.bodyEnd; tok2 = tok2->next()) { if (tok2->str() == "{") { ++indentlevel; continue; } if (tok2->str() == "}") { if (indentlevel > 0U) --indentlevel; else if (Token::simpleMatch(tok2, "} else {")) tok2 = tok2->linkAt(2); continue; } if (tok2->varId() == var->declarationId()) { if (Token::simpleMatch(tok2->next(), "=")) break; dereferenceErasedError(tok, tok2, tok2->str(), inconclusiveType); break; } if (indentlevel == 0U && Token::Match(tok2, "break|return|goto")) break; } if (tok2 == scope.bodyEnd) dereferenceErasedError(tok, scope.classDef, var->nameToken()->str(), inconclusiveType); } } void CheckStl::pushback() { // Pointer can become invalid after push_back, push_front, reserve or resize.. const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "%var% = & %var% [")) { // Skip it directly if it is a pointer or an array const Token* containerTok = tok->tokAt(3); if (containerTok->variable() && containerTok->variable()->isArrayOrPointer()) continue; // Variable id for pointer const unsigned int pointerId(tok->varId()); bool invalidPointer = false; const Token* function = nullptr; const Token* end2 = tok->scope()->bodyEnd; for (const Token *tok2 = tok; tok2 != end2; tok2 = tok2->next()) { // push_back on vector.. if (Token::Match(tok2, "%varid% . push_front|push_back|insert|reserve|resize|clear", containerTok->varId())) { invalidPointer = true; function = tok2->tokAt(2); } // Using invalid pointer.. if (invalidPointer && tok2->varId() == pointerId) { bool unknown = false; if (CheckNullPointer::isPointerDeRef(tok2, unknown)) invalidPointerError(tok2, function->str(), tok2->str()); break; } } } } } // Iterator becomes invalid after reserve, resize, insert, push_back or push_front.. for (const Variable* var : symbolDatabase->variableList()) { // Check that its an iterator if (!var || !var->isLocal() || !Token::Match(var->typeEndToken(), "iterator|const_iterator|reverse_iterator|const_reverse_iterator")) continue; const unsigned int iteratorId = var->declarationId(); // ... on std::vector if (!Token::Match(var->typeStartToken(), "std| ::| vector <")) continue; // the variable id for the vector unsigned int vectorid = 0; const Token* validatingToken = nullptr; std::string invalidIterator; const Token* end2 = var->scope()->bodyEnd; for (const Token *tok2 = var->nameToken(); tok2 != end2; tok2 = tok2->next()) { if (validatingToken == tok2) { invalidIterator.clear(); validatingToken = nullptr; } // Using push_back or push_front inside a loop.. if (Token::simpleMatch(tok2, "for (")) { tok2 = tok2->tokAt(2); } if (Token::Match(tok2, "%varid% = %var% . begin|rbegin|cbegin|crbegin ( ) ; %varid% != %var% . end|rend|cend|crend ( ) ; ++| %varid% ++| ) {", iteratorId)) { // variable id for the loop iterator const unsigned int varId(tok2->tokAt(2)->varId()); const Token *pushbackTok = nullptr; // Count { and } for tok3 const Token *tok3 = tok2->tokAt(20); for (const Token* const end3 = tok3->linkAt(-1); tok3 != end3; tok3 = tok3->next()) { if (tok3->str() == "break" || tok3->str() == "return") { pushbackTok = nullptr; break; } else if (Token::Match(tok3, "%varid% . push_front|push_back|insert|reserve|resize|clear|erase (", varId) && !tok3->previous()->isAssignmentOp()) { if (tok3->strAt(2) != "erase" || (tok3->tokAt(4)->varId() != iteratorId && tok3->tokAt(5)->varId() != iteratorId)) // This case is handled in: CheckStl::iterators() pushbackTok = tok3->tokAt(2); } } if (pushbackTok) invalidIteratorError(pushbackTok, pushbackTok->str(), tok2->str()); } // Assigning iterator.. if (Token::Match(tok2, "%varid% =", iteratorId)) { if (Token::Match(tok2->tokAt(2), "%var% . begin|end|rbegin|rend|cbegin|cend|crbegin|crend|insert|erase|find (")) { if (!invalidIterator.empty() && Token::Match(tok2->tokAt(4), "insert|erase ( *| %varid% )|,", iteratorId)) { invalidIteratorError(tok2, invalidIterator, var->name()); break; } vectorid = tok2->tokAt(2)->varId(); tok2 = tok2->linkAt(5); } else { vectorid = 0; } invalidIterator.clear(); } // push_back on vector.. if (vectorid > 0 && Token::Match(tok2, "%varid% . push_front|push_back|insert|reserve|resize|clear|erase (", vectorid)) { if (!invalidIterator.empty() && Token::Match(tok2->tokAt(2), "insert|erase ( *| %varid% ,|)", iteratorId)) { invalidIteratorError(tok2, invalidIterator, var->name()); break; } if (tok2->strAt(2) != "erase" || (tok2->tokAt(4)->varId() != iteratorId && tok2->tokAt(5)->varId() != iteratorId)) // This case is handled in: CheckStl::iterators() invalidIterator = tok2->strAt(2); tok2 = tok2->linkAt(3); } else if (tok2->str() == "return" || tok2->str() == "throw") validatingToken = Token::findsimplematch(tok2->next(), ";"); // TODO: instead of bail out for 'else' try to check all execution paths. else if (tok2->str() == "break" || tok2->str() == "else") invalidIterator.clear(); // Using invalid iterator.. if (!invalidIterator.empty()) { if (Token::Match(tok2, "++|--|*|+|-|(|,|=|!= %varid%", iteratorId)) invalidIteratorError(tok2, invalidIterator, tok2->strAt(1)); if (Token::Match(tok2, "%varid% ++|--|+|-|.", iteratorId)) invalidIteratorError(tok2, invalidIterator, tok2->str()); } } } } // Error message for bad iterator usage.. void CheckStl::invalidIteratorError(const Token *tok, const std::string &func, const std::string &iterator_name) { reportError(tok, Severity::error, "invalidIterator2", "$symbol:" + func + "\n" "$symbol:" + iterator_name + "\n" "After " + func + "(), the iterator '" + iterator_name + "' may be invalid.", CWE664, false); } // Error message for bad iterator usage.. void CheckStl::invalidPointerError(const Token *tok, const std::string &func, const std::string &pointer_name) { reportError(tok, Severity::error, "invalidPointer", "$symbol:" + func + "\n" "$symbol:" + pointer_name + "\n" "Invalid pointer '" + pointer_name + "' after " + func + "().", CWE664, false); } void CheckStl::stlBoundaries() { const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable* var : symbolDatabase->variableList()) { if (!var || !var->scope() || !var->scope()->isExecutable()) continue; const Library::Container* container = mSettings->library.detectContainer(var->typeStartToken(), true); if (!container || container->opLessAllowed) continue; const Token* const end = var->scope()->bodyEnd; for (const Token *tok = var->nameToken(); tok != end; tok = tok->next()) { if (Token::Match(tok, "!!* %varid% <", var->declarationId())) { stlBoundariesError(tok); } else if (Token::Match(tok, "> %varid% !!.", var->declarationId())) { stlBoundariesError(tok); } } } } // Error message for bad boundary usage.. void CheckStl::stlBoundariesError(const Token *tok) { reportError(tok, Severity::error, "stlBoundaries", "Dangerous comparison using operator< on iterator.\n" "Iterator compared with operator<. This is dangerous since the order of items in the " "container is not guaranteed. One should use operator!= instead to compare iterators.", CWE664, false); } static bool if_findCompare(const Token * const tokBack) { const Token *tok = tokBack->astParent(); if (!tok) return true; if (tok->isComparisonOp()) return (!tok->astOperand1()->isNumber() && !tok->astOperand2()->isNumber()); if (tok->isArithmeticalOp()) // result is used in some calculation return true; // TODO: check if there is a comparison of the result somewhere if (tok->str() == ".") return true; // Dereferencing is OK, the programmer might know that the element exists - TODO: An inconclusive warning might be appropriate if (tok->isAssignmentOp()) return if_findCompare(tok); // Go one step upwards in the AST return false; } void CheckStl::if_find() { const bool printWarning = mSettings->isEnabled(Settings::WARNING); const bool printPerformance = mSettings->isEnabled(Settings::PERFORMANCE); if (!printWarning && !printPerformance) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope &scope : symbolDatabase->scopeList) { if ((scope.type != Scope::eIf && scope.type != Scope::eWhile) || !scope.classDef) continue; for (const Token *tok = scope.classDef->next(); tok->str() != "{"; tok = tok->next()) { const Token* funcTok = nullptr; const Library::Container* container = nullptr; if (Token::Match(tok, "%name% (")) tok = tok->linkAt(1); else if (tok->variable() && Token::Match(tok, "%var% . %name% (")) { container = mSettings->library.detectContainer(tok->variable()->typeStartToken()); funcTok = tok->tokAt(2); } // check also for vector-like or pointer containers else if (tok->variable() && tok->astParent() && (tok->astParent()->str() == "*" || tok->astParent()->str() == "[")) { const Token *tok2 = tok->astParent(); if (!Token::Match(tok2->astParent(), ". %name% (")) continue; funcTok = tok2->astParent()->next(); if (tok->variable()->isArrayOrPointer()) container = mSettings->library.detectContainer(tok->variable()->typeStartToken()); else { // Container of container - find the inner container container = mSettings->library.detectContainer(tok->variable()->typeStartToken()); // outer container tok2 = Token::findsimplematch(tok->variable()->typeStartToken(), "<", tok->variable()->typeEndToken()); if (container && container->type_templateArgNo >= 0 && tok2) { tok2 = tok2->next(); for (int j = 0; j < container->type_templateArgNo; j++) tok2 = tok2->nextTemplateArgument(); container = mSettings->library.detectContainer(tok2); // innner container } else container = nullptr; } } if (container && container->getAction(funcTok->str()) == Library::Container::FIND) { if (if_findCompare(funcTok->next())) continue; if (printWarning && container->getYield(funcTok->str()) == Library::Container::ITERATOR) if_findError(tok, false); else if (printPerformance && container->stdStringLike && funcTok->str() == "find") if_findError(tok, true); } else if (printWarning && Token::Match(tok, "std :: find|find_if (")) { // check that result is checked properly if (!if_findCompare(tok->tokAt(3))) { if_findError(tok, false); } } } } } void CheckStl::if_findError(const Token *tok, bool str) { if (str) reportError(tok, Severity::performance, "stlIfStrFind", "Inefficient usage of string::find() in condition; string::compare() would be faster.\n" "Either inefficient or wrong usage of string::find(). string::compare() will be faster if " "string::find's result is compared with 0, because it will not scan the whole " "string. If your intention is to check that there are no findings in the string, " "you should compare with std::string::npos.", CWE597, false); else reportError(tok, Severity::warning, "stlIfFind", "Suspicious condition. The result of find() is an iterator, but it is not properly checked.", CWE398, false); } /** * Is container.size() slow? */ static bool isCpp03ContainerSizeSlow(const Token *tok) { if (!tok) return false; const Variable* var = tok->variable(); return var && var->isStlType("list"); } void CheckStl::size() { if (!mSettings->isEnabled(Settings::PERFORMANCE)) return; if (mSettings->standards.cpp == Standards::CPP11) return; const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "%var% . size ( )") || Token::Match(tok, "%name% . %var% . size ( )")) { // get the variable const Token *varTok = tok; if (tok->strAt(2) != "size") varTok = varTok->tokAt(2); const Token* const end = varTok->tokAt(5); // check for comparison to zero if ((tok->previous() && !tok->previous()->isArithmeticalOp() && Token::Match(end, "==|<=|!=|> 0")) || (end->next() && !end->next()->isArithmeticalOp() && Token::Match(tok->tokAt(-2), "0 ==|>=|!=|<"))) { if (isCpp03ContainerSizeSlow(varTok)) { sizeError(varTok); continue; } } // check for comparison to one if ((tok->previous() && !tok->previous()->isArithmeticalOp() && Token::Match(end, ">=|< 1") && !end->tokAt(2)->isArithmeticalOp()) || (end->next() && !end->next()->isArithmeticalOp() && Token::Match(tok->tokAt(-2), "1 <=|>") && !tok->tokAt(-3)->isArithmeticalOp())) { if (isCpp03ContainerSizeSlow(varTok)) sizeError(varTok); } // check for using as boolean expression else if ((Token::Match(tok->tokAt(-2), "if|while (") && end->str() == ")") || (tok->previous()->tokType() == Token::eLogicalOp && Token::Match(end, "&&|)|,|;|%oror%"))) { if (isCpp03ContainerSizeSlow(varTok)) sizeError(varTok); } } } } } void CheckStl::sizeError(const Token *tok) { const std::string varname = tok ? tok->str() : std::string("list"); reportError(tok, Severity::performance, "stlSize", "$symbol:" + varname + "\n" "Possible inefficient checking for '$symbol' emptiness.\n" "Checking for '$symbol' emptiness might be inefficient. " "Using $symbol.empty() instead of $symbol.size() can be faster. " "$symbol.size() can take linear time but $symbol.empty() is " "guaranteed to take constant time.", CWE398, false); } void CheckStl::redundantCondition() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope &scope : symbolDatabase->scopeList) { if (scope.type != Scope::eIf) continue; const Token* tok = scope.classDef->tokAt(2); if (!Token::Match(tok, "%name% . find ( %any% ) != %name% . end|rend|cend|crend ( ) ) { %name% . remove|erase ( %any% ) ;")) continue; // Get tokens for the fields %name% and %any% const Token *var1 = tok; const Token *any1 = var1->tokAt(4); const Token *var2 = any1->tokAt(3); const Token *var3 = var2->tokAt(7); const Token *any2 = var3->tokAt(4); // Check if all the "%name%" fields are the same and if all the "%any%" are the same.. if (var1->str() == var2->str() && var2->str() == var3->str() && any1->str() == any2->str()) { redundantIfRemoveError(tok); } } } void CheckStl::redundantIfRemoveError(const Token *tok) { reportError(tok, Severity::style, "redundantIfRemove", "Redundant checking of STL container element existence before removing it.\n" "Redundant checking of STL container element existence before removing it. " "It is safe to call the remove method on a non-existing element.", CWE398, false); } void CheckStl::missingComparison() { if (!mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope &scope : symbolDatabase->scopeList) { if (scope.type != Scope::eFor || !scope.classDef) continue; for (const Token *tok2 = scope.classDef->tokAt(2); tok2 != scope.bodyStart; tok2 = tok2->next()) { if (tok2->str() == ";") break; if (!Token::Match(tok2, "%var% = %name% . begin|rbegin|cbegin|crbegin ( ) ; %name% != %name% . end|rend|cend|crend ( ) ; ++| %name% ++| ) {")) continue; // same container if (tok2->strAt(2) != tok2->strAt(10)) break; const unsigned int iteratorId(tok2->varId()); // same iterator if (iteratorId == tok2->tokAt(10)->varId()) break; // increment iterator if (!Token::Match(tok2->tokAt(16), "++ %varid% )", iteratorId) && !Token::Match(tok2->tokAt(16), "%varid% ++ )", iteratorId)) { break; } const Token *incrementToken = nullptr; // Parse loop.. for (const Token *tok3 = scope.bodyStart; tok3 != scope.bodyEnd; tok3 = tok3->next()) { if (Token::Match(tok3, "%varid% ++", iteratorId)) incrementToken = tok3; else if (Token::Match(tok3->previous(), "++ %varid% !!.", iteratorId)) incrementToken = tok3; else if (Token::Match(tok3, "%varid% !=|==", iteratorId)) incrementToken = nullptr; else if (tok3->str() == "break" || tok3->str() == "return") incrementToken = nullptr; else if (Token::Match(tok3, "%varid% = %name% . insert ( ++| %varid% ++| ,", iteratorId)) { // skip insertion.. tok3 = tok3->linkAt(6); if (!tok3) break; } } if (incrementToken) missingComparisonError(incrementToken, tok2->tokAt(16)); } } } void CheckStl::missingComparisonError(const Token *incrementToken1, const Token *incrementToken2) { std::list callstack = { incrementToken1,incrementToken2 }; std::ostringstream errmsg; errmsg << "Missing bounds check for extra iterator increment in loop.\n" << "The iterator incrementing is suspicious - it is incremented at line "; if (incrementToken1) errmsg << incrementToken1->linenr(); errmsg << " and then at line "; if (incrementToken2) errmsg << incrementToken2->linenr(); errmsg << ". The loop might unintentionally skip an element in the container. " << "There is no comparison between these increments to prevent that the iterator is " << "incremented beyond the end."; reportError(callstack, Severity::warning, "StlMissingComparison", errmsg.str(), CWE834, false); } static bool isLocal(const Token *tok) { const Variable *var = tok->variable(); return var && !var->isStatic() && var->isLocal(); } namespace { const std::set stl_string_stream = { "istringstream", "ostringstream", "stringstream", "wstringstream" }; } void CheckStl::string_c_str() { const bool printInconclusive = mSettings->inconclusive; const bool printPerformance = mSettings->isEnabled(Settings::PERFORMANCE); const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase(); // Find all functions that take std::string as argument std::multimap c_strFuncParam; if (printPerformance) { for (const Scope &scope : symbolDatabase->scopeList) { for (const Function &func : scope.functionList) { if (c_strFuncParam.erase(func.tokenDef->str()) != 0) { // Check if function with this name was already found c_strFuncParam.insert(std::make_pair(func.tokenDef->str(), 0)); // Disable, because there are overloads. TODO: Handle overloads continue; } unsigned int numpar = 0; c_strFuncParam.insert(std::make_pair(func.tokenDef->str(), numpar)); // Insert function as dummy, to indicate that there is at least one function with that name for (const Variable &var : func.argumentList) { numpar++; if (var.isStlStringType() && (!var.isReference() || var.isConst())) c_strFuncParam.insert(std::make_pair(func.tokenDef->str(), numpar)); } } } } // Try to detect common problems when using string::c_str() for (const Scope &scope : symbolDatabase->scopeList) { if (scope.type != Scope::eFunction || !scope.function) continue; enum {charPtr, stdString, stdStringConstRef, Other} returnType = Other; if (Token::Match(scope.function->tokenDef->tokAt(-2), "char|wchar_t *")) returnType = charPtr; else if (Token::Match(scope.function->tokenDef->tokAt(-5), "const std :: string|wstring &")) returnType = stdStringConstRef; else if (Token::Match(scope.function->tokenDef->tokAt(-3), "std :: string|wstring !!&")) returnType = stdString; for (const Token *tok = scope.bodyStart; tok && tok != scope.bodyEnd; tok = tok->next()) { // Invalid usage.. if (Token::Match(tok, "throw %var% . c_str|data ( ) ;") && isLocal(tok->next()) && tok->next()->variable() && tok->next()->variable()->isStlStringType()) { string_c_strThrowError(tok); } else if (Token::Match(tok, "[;{}] %name% = %var% . str ( ) . c_str|data ( ) ;")) { const Variable* var = tok->next()->variable(); const Variable* var2 = tok->tokAt(3)->variable(); if (var && var->isPointer() && var2 && var2->isStlType(stl_string_stream)) string_c_strError(tok); } else if (Token::Match(tok, "[;{}] %var% = %name% (") && Token::Match(tok->linkAt(4), ") . c_str|data ( ) ;") && tok->tokAt(3)->function() && Token::Match(tok->tokAt(3)->function()->retDef, "std :: string|wstring %name%")) { const Variable* var = tok->next()->variable(); if (var && var->isPointer()) string_c_strError(tok); } else if (printPerformance && Token::Match(tok, "%name% ( !!)") && c_strFuncParam.find(tok->str()) != c_strFuncParam.end() && !Token::Match(tok->previous(), "::|.") && tok->varId() == 0 && tok->str() != scope.className) { // calling function. TODO: Add support for member functions const std::pair::const_iterator, std::multimap::const_iterator> range = c_strFuncParam.equal_range(tok->str()); for (std::multimap::const_iterator i = range.first; i != range.second; ++i) { if (i->second == 0) continue; const Token* tok2 = tok->tokAt(2); unsigned int j; for (j = 0; tok2 && j < i->second-1; j++) tok2 = tok2->nextArgument(); if (tok2) tok2 = tok2->nextArgument(); else break; if (!tok2 && j == i->second-1) tok2 = tok->next()->link(); else if (tok2) tok2 = tok2->previous(); else break; if (tok2 && Token::Match(tok2->tokAt(-4), ". c_str|data ( )")) { const Variable* var = tok2->tokAt(-5)->variable(); if (var && var->isStlStringType()) { string_c_strParam(tok, i->second); } else if (Token::Match(tok2->tokAt(-9), "%name% . str ( )")) { // Check ss.str().c_str() as parameter const Variable* ssVar = tok2->tokAt(-9)->variable(); if (ssVar && ssVar->isStlType(stl_string_stream)) string_c_strParam(tok, i->second); } } } } // Using c_str() to get the return value is only dangerous if the function returns a char* if ((returnType == charPtr || (printPerformance && (returnType == stdString || returnType == stdStringConstRef))) && tok->str() == "return") { bool err = false; const Token* tok2 = tok->next(); if (Token::Match(tok2, "std :: string|wstring (") && Token::Match(tok2->linkAt(3), ") . c_str|data ( ) ;")) { err = true; } else if (Token::simpleMatch(tok2, "(") && Token::Match(tok2->link(), ") . c_str|data ( ) ;")) { // Check for "+ localvar" or "+ std::string(" inside the bracket bool is_implicit_std_string = printInconclusive; const Token *search_end = tok2->link(); for (const Token *search_tok = tok2->next(); search_tok != search_end; search_tok = search_tok->next()) { if (Token::Match(search_tok, "+ %var%") && isLocal(search_tok->next()) && search_tok->next()->variable() && search_tok->next()->variable()->isStlStringType()) { is_implicit_std_string = true; break; } else if (Token::Match(search_tok, "+ std :: string|wstring (")) { is_implicit_std_string = true; break; } } if (is_implicit_std_string) err = true; } bool local = false; bool ptrOrRef = false; const Variable* lastVar = nullptr; const Function* lastFunc = nullptr; bool funcStr = false; if (Token::Match(tok2, "%var% .")) { local = isLocal(tok2); bool refToNonLocal = false; if (tok2->variable() && tok2->variable()->isReference()) { const Token *refTok = tok2->variable()->nameToken(); refToNonLocal = true; // safe assumption is default to avoid FPs if (Token::Match(refTok, "%var% = %var% .|;|[")) refToNonLocal = !isLocal(refTok->tokAt(2)); } ptrOrRef = refToNonLocal || (tok2->variable() && tok2->variable()->isPointer()); } while (tok2) { if (Token::Match(tok2, "%var% .|::")) { if (ptrOrRef) local = false; lastVar = tok2->variable(); tok2 = tok2->tokAt(2); } else if (Token::Match(tok2, "%name% (") && Token::simpleMatch(tok2->linkAt(1), ") .")) { lastFunc = tok2->function(); local = false; funcStr = tok2->str() == "str"; tok2 = tok2->linkAt(1)->tokAt(2); } else break; } if (Token::Match(tok2, "c_str|data ( ) ;")) { if ((local || returnType != charPtr) && lastVar && lastVar->isStlStringType()) err = true; else if (funcStr && lastVar && lastVar->isStlType(stl_string_stream)) err = true; else if (lastFunc && Token::Match(lastFunc->tokenDef->tokAt(-3), "std :: string|wstring")) err = true; } if (err) { if (returnType == charPtr) string_c_strError(tok); else string_c_strReturn(tok); } } } } } void CheckStl::string_c_strThrowError(const Token* tok) { reportError(tok, Severity::error, "stlcstrthrow", "Dangerous usage of c_str(). The value returned by c_str() is invalid after throwing exception.\n" "Dangerous usage of c_str(). The string is destroyed after the c_str() call so the thrown pointer is invalid."); } void CheckStl::string_c_strError(const Token* tok) { reportError(tok, Severity::error, "stlcstr", "Dangerous usage of c_str(). The value returned by c_str() is invalid after this call.\n" "Dangerous usage of c_str(). The c_str() return value is only valid until its string is deleted.", CWE664, false); } void CheckStl::string_c_strReturn(const Token* tok) { reportError(tok, Severity::performance, "stlcstrReturn", "Returning the result of c_str() in a function that returns std::string is slow and redundant.\n" "The conversion from const char* as returned by c_str() to std::string creates an unnecessary string copy. Solve that by directly returning the string.", CWE704, false); } void CheckStl::string_c_strParam(const Token* tok, unsigned int number) { std::ostringstream oss; oss << "Passing the result of c_str() to a function that takes std::string as argument no. " << number << " is slow and redundant.\n" "The conversion from const char* as returned by c_str() to std::string creates an unnecessary string copy. Solve that by directly passing the string."; reportError(tok, Severity::performance, "stlcstrParam", oss.str(), CWE704, false); } static bool hasArrayEnd(const Token *tok1) { const Token *end = Token::findsimplematch(tok1, ";"); return (end && Token::simpleMatch(end->previous(), "] ;")); } static bool hasArrayEndParen(const Token *tok1) { const Token *end = Token::findsimplematch(tok1, ";"); return (end && end->previous() && Token::simpleMatch(end->tokAt(-2), "] ) ;")); } //--------------------------------------------------------------------------- // //--------------------------------------------------------------------------- void CheckStl::checkAutoPointer() { std::set autoPtrVarId; std::map mallocVarId; // variables allocated by the malloc-like function const char STL_CONTAINER_LIST[] = "array|bitset|deque|list|forward_list|map|multimap|multiset|priority_queue|queue|set|stack|vector|hash_map|hash_multimap|hash_set|unordered_map|unordered_multimap|unordered_set|unordered_multiset|basic_string"; const int malloc = mSettings->library.allocId("malloc"); // allocation function, which are not compatible with auto_ptr const bool printStyle = mSettings->isEnabled(Settings::STYLE); for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (Token::simpleMatch(tok, "auto_ptr <")) { if ((tok->strAt(-1) == "<" && Token::Match(tok->tokAt(-2), STL_CONTAINER_LIST)) || (Token::simpleMatch(tok->tokAt(-3), "< std :: auto_ptr") && Token::Match(tok->tokAt(-4), STL_CONTAINER_LIST))) { autoPointerContainerError(tok); } else { const Token *tok2 = tok->linkAt(1); if (Token::Match(tok2, "> %name%")) { const Token *tok3 = tok2->tokAt(2); if (Token::Match(tok3, "( new %type%") && hasArrayEndParen(tok3)) { autoPointerArrayError(tok2->next()); } if (Token::Match(tok3, "( %name% (") && malloc && mSettings->library.alloc(tok3->next(), -1) == malloc) { // malloc-like function allocated memory passed to the auto_ptr constructor -> error autoPointerMallocError(tok2->next(), tok3->next()->str()); } if (Token::Match(tok3, "( %var%")) { const std::map::const_iterator it = mallocVarId.find(tok3->next()->varId()); if (it != mallocVarId.cend()) { // pointer on the memory allocated by malloc used in the auto pointer constructor -> error autoPointerMallocError(tok2->next(), it->second); } } while (tok3 && tok3->str() != ";") { tok3 = tok3->next(); } if (tok3) { tok3 = tok3->tokAt(-2); if (Token::simpleMatch(tok3->previous(), "[ ] )")) { autoPointerArrayError(tok2->next()); } else if (tok3->varId()) { const Token *decltok = Token::findmatch(mTokenizer->tokens(), "%varid% = new %type%", tok3->varId()); if (decltok && hasArrayEnd(decltok)) { autoPointerArrayError(tok2->next()); } } if (tok2->next()->varId()) { autoPtrVarId.insert(tok2->next()->varId()); } } } } } else { if (Token::Match(tok, "%name% = %var% ;")) { if (printStyle) { const std::set::const_iterator iter = autoPtrVarId.find(tok->tokAt(2)->varId()); if (iter != autoPtrVarId.end()) { autoPointerError(tok->tokAt(2)); } } } else if ((Token::Match(tok, "%var% = new %type%") && hasArrayEnd(tok)) || (Token::Match(tok, "%var% . reset ( new %type%") && hasArrayEndParen(tok))) { const std::set::const_iterator iter = autoPtrVarId.find(tok->varId()); if (iter != autoPtrVarId.end()) { autoPointerArrayError(tok); } } else if (Token::Match(tok, "%var% = %name% (") && malloc && mSettings->library.alloc(tok->tokAt(2), -1) == malloc) { // C library function like 'malloc' used together with auto pointer -> error const std::set::const_iterator iter = autoPtrVarId.find(tok->varId()); if (iter != autoPtrVarId.end()) { autoPointerMallocError(tok, tok->strAt(2)); } else if (tok->varId()) { // it is not an auto pointer variable and it is allocated by malloc like function. mallocVarId.insert(std::make_pair(tok->varId(), tok->strAt(2))); } } else if (Token::Match(tok, "%var% . reset ( %name% (") && malloc && mSettings->library.alloc(tok->tokAt(4), -1) == malloc) { // C library function like 'malloc' used when resetting auto pointer -> error const std::set::const_iterator iter = autoPtrVarId.find(tok->varId()); if (iter != autoPtrVarId.end()) { autoPointerMallocError(tok, tok->strAt(4)); } } } } } void CheckStl::autoPointerError(const Token *tok) { reportError(tok, Severity::style, "useAutoPointerCopy", "Copying 'auto_ptr' pointer to another does not create two equal objects since one has lost its ownership of the pointer.\n" "'std::auto_ptr' has semantics of strict ownership, meaning that the 'auto_ptr' instance is the sole entity responsible for the object's lifetime. If an 'auto_ptr' is copied, the source looses the reference.", CWE398, false); } void CheckStl::autoPointerContainerError(const Token *tok) { reportError(tok, Severity::error, "useAutoPointerContainer", "You can randomly lose access to pointers if you store 'auto_ptr' pointers in an STL container.\n" "An element of container must be able to be copied but 'auto_ptr' does not fulfill this requirement. You should consider to use 'shared_ptr' or 'unique_ptr'. It is suitable for use in containers, because they no longer copy their values, they move them.", CWE664, false ); } void CheckStl::autoPointerArrayError(const Token *tok) { reportError(tok, Severity::error, "useAutoPointerArray", "Object pointed by an 'auto_ptr' is destroyed using operator 'delete'. You should not use 'auto_ptr' for pointers obtained with operator 'new[]'.\n" "Object pointed by an 'auto_ptr' is destroyed using operator 'delete'. This means that you should only use 'auto_ptr' for pointers obtained with operator 'new'. This excludes arrays, which are allocated by operator 'new[]' and must be deallocated by operator 'delete[]'.", CWE664, false ); } void CheckStl::autoPointerMallocError(const Token *tok, const std::string& allocFunction) { const std::string summary = "Object pointed by an 'auto_ptr' is destroyed using operator 'delete'. You should not use 'auto_ptr' for pointers obtained with function '$symbol'."; const std::string verbose = summary + " This means that you should only use 'auto_ptr' for pointers obtained with operator 'new'. This excludes use C library allocation functions (for example '$symbol'), which must be deallocated by the appropriate C library function."; reportError(tok, Severity::error, "useAutoPointerMalloc", "$symbol:" + allocFunction + '\n' + summary + '\n' + verbose, CWE762, false); } namespace { const std::set stl_containers_with_empty_and_clear = { "deque", "forward_list", "list", "map", "multimap", "multiset", "set", "string", "unordered_map", "unordered_multimap", "unordered_multiset", "unordered_set", "vector", "wstring" }; } void CheckStl::uselessCalls() { const bool printPerformance = mSettings->isEnabled(Settings::PERFORMANCE); const bool printWarning = mSettings->isEnabled(Settings::WARNING); if (!printPerformance && !printWarning) return; const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { if (printWarning && Token::Match(tok, "%var% . compare|find|rfind|find_first_not_of|find_first_of|find_last_not_of|find_last_of ( %name% [,)]") && tok->varId() == tok->tokAt(4)->varId()) { const Variable* var = tok->variable(); if (!var || !var->isStlType()) continue; uselessCallsReturnValueError(tok->tokAt(4), tok->str(), tok->strAt(2)); } else if (printPerformance && Token::Match(tok, "%var% . swap ( %name% )") && tok->varId() == tok->tokAt(4)->varId()) { const Variable* var = tok->variable(); if (!var || !var->isStlType()) continue; uselessCallsSwapError(tok, tok->str()); } else if (printPerformance && Token::Match(tok, "%var% . substr (") && tok->variable() && tok->variable()->isStlStringType()) { if (Token::Match(tok->tokAt(4), "0| )")) { uselessCallsSubstrError(tok, false); } else if (tok->strAt(4) == "0" && tok->linkAt(3)->strAt(-1) == "npos") { if (!tok->linkAt(3)->previous()->variable()) // Make sure that its no variable uselessCallsSubstrError(tok, false); } else if (Token::simpleMatch(tok->linkAt(3)->tokAt(-2), ", 0 )")) uselessCallsSubstrError(tok, true); } else if (printWarning && Token::Match(tok, "[{};] %var% . empty ( ) ;") && !tok->tokAt(4)->astParent() && tok->next()->variable() && tok->next()->variable()->isStlType(stl_containers_with_empty_and_clear)) uselessCallsEmptyError(tok->next()); else if (Token::Match(tok, "[{};] std :: remove|remove_if|unique (") && tok->tokAt(5)->nextArgument()) uselessCallsRemoveError(tok->next(), tok->strAt(3)); } } } void CheckStl::uselessCallsReturnValueError(const Token *tok, const std::string &varname, const std::string &function) { std::ostringstream errmsg; errmsg << "$symbol:" << varname << '\n'; errmsg << "$symbol:" << function << '\n'; errmsg << "It is inefficient to call '" << varname << "." << function << "(" << varname << ")' as it always returns 0.\n" << "'std::string::" << function << "()' returns zero when given itself as parameter " << "(" << varname << "." << function << "(" << varname << ")). As it is currently the " << "code is inefficient. It is possible either the string searched ('" << varname << "') or searched for ('" << varname << "') is wrong."; reportError(tok, Severity::warning, "uselessCallsCompare", errmsg.str(), CWE628, false); } void CheckStl::uselessCallsSwapError(const Token *tok, const std::string &varname) { reportError(tok, Severity::performance, "uselessCallsSwap", "$symbol:" + varname + "\n" "It is inefficient to swap a object with itself by calling '$symbol.swap($symbol)'\n" "The 'swap()' function has no logical effect when given itself as parameter " "($symbol.swap($symbol)). As it is currently the " "code is inefficient. Is the object or the parameter wrong here?", CWE628, false); } void CheckStl::uselessCallsSubstrError(const Token *tok, bool empty) { if (empty) reportError(tok, Severity::performance, "uselessCallsSubstr", "Ineffective call of function 'substr' because it returns an empty string.", CWE398, false); else reportError(tok, Severity::performance, "uselessCallsSubstr", "Ineffective call of function 'substr' because it returns a copy of the object. Use operator= instead.", CWE398, false); } void CheckStl::uselessCallsEmptyError(const Token *tok) { reportError(tok, Severity::warning, "uselessCallsEmpty", "Ineffective call of function 'empty()'. Did you intend to call 'clear()' instead?", CWE398, false); } void CheckStl::uselessCallsRemoveError(const Token *tok, const std::string& function) { reportError(tok, Severity::warning, "uselessCallsRemove", "$symbol:" + function + "\n" "Return value of std::$symbol() ignored. Elements remain in container.\n" "The return value of std::$symbol() is ignored. This function returns an iterator to the end of the range containing those elements that should be kept. " "Elements past new end remain valid but with unspecified values. Use the erase method of the container to delete them.", CWE762, false); } // Check for iterators being dereferenced before being checked for validity. // E.g. if (*i && i != str.end()) { } void CheckStl::checkDereferenceInvalidIterator() { if (!mSettings->isEnabled(Settings::WARNING)) return; // Iterate over "if", "while", and "for" conditions where there may // be an iterator that is dereferenced before being checked for validity. for (const Scope &scope : mTokenizer->getSymbolDatabase()->scopeList) { if (!(scope.type == Scope::eIf || scope.type == Scope::eDo || scope.type == Scope::eWhile || scope.type == Scope::eFor)) continue; const Token* const tok = scope.classDef; const Token* startOfCondition = tok->next(); if (scope.type == Scope::eDo) startOfCondition = startOfCondition->link()->tokAt(2); if (!startOfCondition) // ticket #6626 invalid code continue; const Token* endOfCondition = startOfCondition->link(); if (!endOfCondition) continue; // For "for" loops, only search between the two semicolons if (scope.type == Scope::eFor) { startOfCondition = Token::findsimplematch(tok->tokAt(2), ";", endOfCondition); if (!startOfCondition) continue; endOfCondition = Token::findsimplematch(startOfCondition->next(), ";", endOfCondition); if (!endOfCondition) continue; } // Only consider conditions composed of all "&&" terms and // conditions composed of all "||" terms const bool isOrExpression = Token::findsimplematch(startOfCondition, "||", endOfCondition) != nullptr; const bool isAndExpression = Token::findsimplematch(startOfCondition, "&&", endOfCondition) != nullptr; // Look for a check of the validity of an iterator const Token* validityCheckTok = nullptr; if (!isOrExpression && isAndExpression) { validityCheckTok = Token::findmatch(startOfCondition, "&& %var% != %name% . end|rend|cend|crend ( )", endOfCondition); } else if (isOrExpression && !isAndExpression) { validityCheckTok = Token::findmatch(startOfCondition, "%oror% %var% == %name% . end|rend|cend|crend ( )", endOfCondition); } if (!validityCheckTok) continue; const unsigned int iteratorVarId = validityCheckTok->next()->varId(); // If the iterator dereference is to the left of the check for // the iterator's validity, report an error. const Token* const dereferenceTok = Token::findmatch(startOfCondition, "* %varid%", validityCheckTok, iteratorVarId); if (dereferenceTok) dereferenceInvalidIteratorError(dereferenceTok, dereferenceTok->strAt(1)); } } void CheckStl::dereferenceInvalidIteratorError(const Token* deref, const std::string &iterName) { reportError(deref, Severity::warning, "derefInvalidIterator", "$symbol:" + iterName + "\n" "Possible dereference of an invalid iterator: $symbol\n" "Possible dereference of an invalid iterator: $symbol. Make sure to check that the iterator is valid before dereferencing it - not after.", CWE825, false); } void CheckStl::readingEmptyStlContainer_parseUsage(const Token* tok, const Library::Container* container, std::map& empty, bool noerror) { // Check for various conditions for the way stl containers and variables can be used if (tok->strAt(1) == "=" || (tok->strAt(1) == "[" && Token::simpleMatch(tok->linkAt(1), "] ="))) { // Assignment (LHS) empty.erase(tok->varId()); } else if (Token::Match(tok, "%name% [")) { // Access through operator[] if (!container->arrayLike_indexOp) { // operator[] inserts an element if used on a std::map if (!noerror && tok->strAt(-1) == "=") readingEmptyStlContainerError(tok); empty.erase(tok->varId()); } else if (!noerror) readingEmptyStlContainerError(tok); } else if (Token::Match(tok, "%name% . %type% (")) { // Member function call const Library::Container::Action action = container->getAction(tok->strAt(2)); if ((action == Library::Container::FIND || action == Library::Container::ERASE || action == Library::Container::POP || action == Library::Container::CLEAR) && !noerror) { readingEmptyStlContainerError(tok); return; } const Token* parent = tok->tokAt(3)->astParent(); const Library::Container::Yield yield = container->getYield(tok->strAt(2)); const bool yieldsIterator = (yield == Library::Container::ITERATOR || yield == Library::Container::START_ITERATOR || yield == Library::Container::END_ITERATOR); if (yield != Library::Container::NO_YIELD && (!parent || Token::Match(parent, "%cop%|*") || parent->isAssignmentOp() || !yieldsIterator)) { // These functions read from the container if (!noerror && (!yieldsIterator || !parent || !parent->isAssignmentOp())) readingEmptyStlContainerError(tok); } else empty.erase(tok->varId()); } else if (tok->strAt(-1) == "=") { // Assignment (RHS) if (!noerror) readingEmptyStlContainerError(tok); } else { // Unknown usage. Assume it is initialized. empty.erase(tok->varId()); } } void CheckStl::readingEmptyStlContainer() { if (!mSettings->isEnabled(Settings::STYLE)) return; if (!mSettings->inconclusive) return; std::map emptyContainer; for (const Scope &scope : mTokenizer->getSymbolDatabase()->scopeList) { if (scope.type != Scope::eFunction) continue; for (const Token *tok = scope.bodyStart->next(); tok != scope.bodyEnd; tok = tok->next()) { if (Token::Match(tok, "for|while")) { // Loops and end of scope clear the sets. const Token* tok2 = tok->linkAt(1); if (!tok2) continue; tok2 = tok2->next(); for (const Token* end2 = tok2->link(); tok2 && tok2 != end2; tok2 = tok2->next()) { if (!tok2->varId()) continue; const std::map::const_iterator container = emptyContainer.find(tok2->varId()); if (container == emptyContainer.end()) continue; readingEmptyStlContainer_parseUsage(tok2, container->second, emptyContainer, true); } } else if (Token::Match(tok, "do|}|break|case")) { emptyContainer.clear(); } else if (tok->str() == "{" && tok->next()->scope()->type == Scope::eLambda) tok = tok->link(); // function call if (Token::Match(tok, "!!. %name% (") && !Token::simpleMatch(tok->linkAt(2), ") {")) { for (std::map::iterator it = emptyContainer.begin(); it != emptyContainer.end();) { const Variable *var = mTokenizer->getSymbolDatabase()->getVariableFromVarId(it->first); if (var && (var->isLocal() || var->isArgument())) ++it; else emptyContainer.erase(it++); } } if (!tok->varId()) continue; // Check whether a variable should be marked as "empty" const Variable* var = tok->variable(); if (var && !var->isArrayOrPointer() && !var->typeStartToken()->isStandardType()) { bool insert = false; if (var->nameToken() == tok && var->isLocal() && !var->isStatic()) { // Local variable declared insert = !Token::Match(tok->next(), "[(=:]"); // Only if not initialized } else if (Token::Match(tok, "%var% . clear ( ) ;")) { insert = true; } if (insert) { const Library::Container* container = mSettings->library.detectContainer(var->typeStartToken()); if (container) emptyContainer[var->declarationId()] = container; continue; } } const std::map::const_iterator container = emptyContainer.find(tok->varId()); if (container == emptyContainer.end()) continue; readingEmptyStlContainer_parseUsage(tok, container->second, emptyContainer, false); } emptyContainer.clear(); } } void CheckStl::readingEmptyStlContainer2() { for (const Scope *function : mTokenizer->getSymbolDatabase()->functionScopes) { for (const Token *tok = function->bodyStart; tok != function->bodyEnd; tok = tok->next()) { if (!tok->isName() || !tok->valueType()) continue; const Library::Container *container = tok->valueType()->container; if (!container) continue; const ValueFlow::Value *value = tok->getContainerSizeValue(0); if (!value) continue; if (value->isInconclusive() && !mSettings->inconclusive) continue; if (!value->errorSeverity() && !mSettings->isEnabled(Settings::WARNING)) continue; if (Token::Match(tok, "%name% . %name% (")) { if (container->getYield(tok->strAt(2)) == Library::Container::Yield::ITEM) readingEmptyStlContainerError(tok,value); } } } } void CheckStl::readingEmptyStlContainerError(const Token *tok, const ValueFlow::Value *value) { const std::string varname = tok ? tok->str() : std::string("var"); std::string errmsg; if (value && value->condition) errmsg = "Reading from container '$symbol'. " + ValueFlow::eitherTheConditionIsRedundant(value->condition) + " or '$symbol' can be empty."; else errmsg = "Reading from empty STL container '$symbol'"; const ErrorPath errorPath = getErrorPath(tok, value, "Reading from empty container"); reportError(errorPath, value ? (value->errorSeverity() ? Severity::error : Severity::warning) : Severity::style, "reademptycontainer", "$symbol:" + varname +"\n" + errmsg, CWE398, !value); }