/* * Cppcheck - A tool for static C/C++ code analysis * Copyright (C) 2007-2021 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 "bughuntingchecks.h" #include "astutils.h" #include "errorlogger.h" #include "errortypes.h" #include "library.h" #include "mathlib.h" #include "settings.h" #include "symboldatabase.h" #include "token.h" #include "utils.h" #include "valueflow.h" #include #include #include #include #include #include #include static const CWE CWE_BUFFER_UNDERRUN(786U); // Access of Memory Location Before Start of Buffer static const CWE CWE_BUFFER_OVERRUN(788U); // Access of Memory Location After End of Buffer static float getKnownFloatValue(const Token *tok, float def) { for (const auto &value: tok->values()) { if (value.isKnown() && value.valueType == ValueFlow::Value::ValueType::FLOAT) return value.floatValue; } return def; } static bool isLessThan(ExprEngine::DataBase *dataBase, ExprEngine::ValuePtr lhs, ExprEngine::ValuePtr rhs) { return ExprEngine::BinOpResult("<", lhs, rhs).isTrue(dataBase); } static void arrayIndex(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!Token::simpleMatch(tok->astParent(), "[")) return; int nr = 0; const Token *buf = tok->astParent()->astOperand1(); while (Token::simpleMatch(buf, "[")) { ++nr; buf = buf->astOperand1(); } if (!buf || !buf->variable() || !buf->variable()->isArray() || buf == buf->variable()->nameToken()) // TODO return; const Token *index = tok->astParent()->astOperand2(); if (tok != index) // TODO return; if (buf->variable()->dimensions().size() > nr && buf->variable()->dimensions()[nr].known) { const MathLib::bigint bufSize = buf->variable()->dimensions()[nr].num; if (value.isGreaterThan(dataBase, bufSize - 1)) { const bool bailout = (value.type == ExprEngine::ValueType::BailoutValue); dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingArrayIndexOutOfBounds", "Array index out of bounds, cannot determine that " + index->expressionString() + " is less than " + std::to_string(bufSize), CWE_BUFFER_OVERRUN, false, bailout); } } bool isUnsigned = tok->valueType() && tok->valueType()->sign == ::ValueType::Sign::UNSIGNED; if (!isUnsigned && value.isLessThan(dataBase, 0)) { const bool bailout = (value.type == ExprEngine::ValueType::BailoutValue); dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingArrayIndexNegative", "Array index out of bounds, cannot determine that " + index->expressionString() + " is not negative", CWE_BUFFER_UNDERRUN, false, bailout); } } static void bufferOverflow(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (value.type != ExprEngine::ValueType::FunctionCallArgumentValues) return; if (!Token::simpleMatch(tok, "(") || !Token::Match(tok->previous(), "%name% (")) return; const Library::Function *func = dataBase->settings->library.getFunction(tok->previous()); if (!func) return; const ExprEngine::FunctionCallArgumentValues *functionCallArguments = dynamic_cast(&value); if (!functionCallArguments) return; const std::vector arguments = getArguments(tok); if (functionCallArguments->argValues.size() != arguments.size()) // TODO investigate what to do return; int overflowArgument = 0; bool bailout = false; for (auto argNrChecks: func->argumentChecks) { const int argnr = argNrChecks.first; const Library::ArgumentChecks &checks = argNrChecks.second; if (argnr <= 0 || argnr > arguments.size() || checks.minsizes.empty()) continue; ExprEngine::ValuePtr argValue = functionCallArguments->argValues[argnr - 1]; if (!argValue || argValue->type == ExprEngine::ValueType::BailoutValue) { overflowArgument = argnr; bailout = true; break; } std::shared_ptr arrayValue = std::dynamic_pointer_cast(argValue); if (!arrayValue || arrayValue->size.size() != 1) { // TODO: implement this properly. overflowArgument = argnr; bailout = true; break; } for (const Library::ArgumentChecks::MinSize &minsize: checks.minsizes) { if (minsize.type == Library::ArgumentChecks::MinSize::Type::ARGVALUE && minsize.arg > 0 && minsize.arg <= arguments.size()) { ExprEngine::ValuePtr otherValue = functionCallArguments->argValues[minsize.arg - 1]; if (!otherValue || otherValue->type == ExprEngine::ValueType::BailoutValue) { overflowArgument = argnr; bailout = true; break; } if (isLessThan(dataBase, arrayValue->size[0], otherValue)) { overflowArgument = argnr; break; } } else if (minsize.type == Library::ArgumentChecks::MinSize::Type::STRLEN && minsize.arg > 0 && minsize.arg <= arguments.size()) { if (func->formatstr) { // TODO: implement this properly. check if minsize refers to a format string and check max length of that.. overflowArgument = argnr; bailout = true; break; } if (Token::Match(arguments[minsize.arg - 1], "%str%")) { const Token * const str = arguments[minsize.arg - 1]; if (arrayValue->size[0]->isLessThan(dataBase, Token::getStrLength(str))) { overflowArgument = argnr; break; } } else { ExprEngine::ValuePtr otherValue = functionCallArguments->argValues[minsize.arg - 1]; if (!otherValue || otherValue->type == ExprEngine::ValueType::BailoutValue) { overflowArgument = argnr; bailout = true; break; } std::shared_ptr arrayValue2 = std::dynamic_pointer_cast(otherValue); if (!arrayValue2 || arrayValue2->size.size() != 1) { overflowArgument = argnr; bailout = true; break; } if (isLessThan(dataBase, arrayValue->size[0], arrayValue2->size[0])) { overflowArgument = argnr; break; } } } } if (overflowArgument > 0) break; } if (overflowArgument == 0) return; dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingBufferOverflow", "Buffer read/write, when calling '" + tok->previous()->str() + "' it cannot be determined that " + std::to_string(overflowArgument) + getOrdinalText(overflowArgument) + " argument is not overflowed", CWE(120), false, bailout); } static void divByZero(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!tok->astParent() || !std::strchr("/%", tok->astParent()->str()[0])) return; if (tok->hasKnownIntValue() && tok->getKnownIntValue() != 0) return; if (tok->isImpossibleIntValue(0)) return; if (value.isUninit(dataBase) && value.type != ExprEngine::ValueType::BailoutValue) return; float f = getKnownFloatValue(tok, 0.0f); if (f > 0.0f || f < 0.0f) return; if (value.type == ExprEngine::ValueType::BailoutValue) { if (Token::simpleMatch(tok->previous(), "sizeof (")) return; } if (tok->astParent()->astOperand2() == tok && value.isEqual(dataBase, 0)) { const char * const id = (tok->valueType() && tok->valueType()->isFloat()) ? "bughuntingDivByZeroFloat" : "bughuntingDivByZero"; const bool bailout = (value.type == ExprEngine::ValueType::BailoutValue); dataBase->reportError(dataBase->settings->clang ? tok : tok->astParent(), Severity::SeverityType::error, id, "There is division, cannot determine that there can't be a division by zero.", CWE(369), false, bailout); } } #ifdef BUG_HUNTING_INTEGEROVERFLOW static void integerOverflow(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!tok->isArithmeticalOp() || !tok->valueType() || !tok->valueType()->isIntegral() || tok->valueType()->pointer > 0) return; const ExprEngine::BinOpResult *b = dynamic_cast(&value); if (!b) return; int bits = getIntBitsFromValueType(tok->valueType(), *dataBase->settings); if (bits == 0 || bits >= 60) return; std::string errorMessage; if (tok->valueType()->sign == ::ValueType::Sign::SIGNED) { MathLib::bigint v = 1LL << (bits - 1); if (b->isGreaterThan(dataBase, v-1)) errorMessage = "greater than " + std::to_string(v - 1); if (b->isLessThan(dataBase, -v)) { if (!errorMessage.empty()) errorMessage += " or "; errorMessage += "less than " + std::to_string(-v); } } else { MathLib::bigint maxValue = (1LL << bits) - 1; if (b->isGreaterThan(dataBase, maxValue)) errorMessage = "greater than " + std::to_string(maxValue); if (b->isLessThan(dataBase, 0)) { if (!errorMessage.empty()) errorMessage += " or "; errorMessage += "less than 0"; } } if (errorMessage.empty()) return; errorMessage = "There is integer arithmetic, cannot determine that there can't be overflow (if result is " + errorMessage + ")."; if (tok->valueType()->sign == ::ValueType::Sign::UNSIGNED) errorMessage += " Note that unsigned integer overflow is defined and will wrap around."; dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingIntegerOverflow", errorMessage, false, value.type == ExprEngine::ValueType::BailoutValue); } #endif /** check if variable is unconditionally assigned */ static bool isVariableAssigned(const Variable *var, const Token *tok, const Token *scopeStart=nullptr) { const Token * const start = scopeStart && precedes(var->nameToken(), scopeStart) ? scopeStart : var->nameToken(); for (const Token *prev = tok->previous(); prev; prev = prev->previous()) { if (!precedes(start, prev)) break; if (prev->str() == "}") { if (Token::simpleMatch(prev->link()->tokAt(-2), "} else {")) { const Token *elseEnd = prev; const Token *elseStart = prev->link(); const Token *ifEnd = elseStart->tokAt(-2); const Token *ifStart = ifEnd->link(); if (isVariableAssigned(var, ifEnd, ifStart) && isVariableAssigned(var, elseEnd, elseStart)) { return true; } } prev = prev->link(); } if (scopeStart && Token::Match(prev, "return|throw|continue|break")) return true; if (Token::Match(prev, "%varid% =", var->declarationId())) { bool usedInRhs = false; visitAstNodes(prev->next()->astOperand2(), [&usedInRhs, var](const Token *tok) { if (tok->varId() == var->declarationId()) { usedInRhs = true; return ChildrenToVisit::done; } return ChildrenToVisit::op1_and_op2; }); if (!usedInRhs) return true; } } return false; } static void uninit(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!tok->astParent()) return; std::string uninitStructMember; if (const auto* structValue = dynamic_cast(&value)) { uninitStructMember = structValue->getUninitStructMember(dataBase); // uninitialized struct member => is there data copy of struct.. if (!uninitStructMember.empty()) { if (!Token::Match(tok->astParent(), "[=,(]")) return; } } bool uninitData = false; if (!value.isUninit(dataBase) && uninitStructMember.empty()) { if (Token::Match(tok->astParent(), "[(,]")) { if (const auto* arrayValue = dynamic_cast(&value)) { uninitData = arrayValue->data.size() >= 1 && arrayValue->data[0].value->isUninit(dataBase); } } if (!uninitData) return; } // container is not uninitialized if (tok->valueType() && tok->valueType()->pointer==0 && tok->valueType()->container) return; // container element is not uninitialized if (tok->str() == "[" && tok->astOperand1() && tok->astOperand1()->valueType() && tok->astOperand1()->valueType()->pointer==0 && tok->astOperand1()->valueType()->container) { if (tok->astOperand1()->valueType()->container->stdStringLike) return; bool pointerType = false; for (const Token *typeTok = tok->astOperand1()->valueType()->containerTypeToken; Token::Match(typeTok, "%name%|*|::|<"); typeTok = typeTok->next()) { if (typeTok->str() == "<" && typeTok->link()) typeTok = typeTok->link(); if (typeTok->str() == "*") pointerType = true; } if (!pointerType) return; } // variable that is not uninitialized.. if (tok->variable() && !tok->variable()->isPointer() && !tok->variable()->isReference()) { // smart pointer is not uninitialized if (tok->variable()->isSmartPointer()) return; // struct if (tok->variable()->type() && tok->variable()->type()->needInitialization == Type::NeedInitialization::False) return; // template variable is not uninitialized if (Token::findmatch(tok->variable()->typeStartToken(), "%name% <", tok->variable()->typeEndToken())) return; } // lhs in assignment if (tok->astParent()->str() == "=" && tok == tok->astParent()->astOperand1()) return; // Avoid FP when there is bailout.. if (value.type == ExprEngine::ValueType::BailoutValue) { if (tok->hasKnownValue()) return; if (!tok->variable()) // FIXME return; // lhs for scope operator if (Token::Match(tok, "%name% ::")) return; if (tok->astParent()->str() == "::" && tok == tok->astParent()->astOperand1()) return; // Object allocated on the stack if (Token::Match(tok, "%var% .") && tok->next()->originalName() != "->") return; // Assume that stream object is initialized if (Token::Match(tok->previous(), "[;{}] %var% <<|>>") && !tok->next()->astParent()) return; // Containers are not uninitialized std::vector tokens{tok, tok->astOperand1(), tok->astOperand2()}; if (Token::Match(tok->previous(), ". %name%")) tokens.push_back(tok->previous()->astOperand1()); for (const Token *t: tokens) { if (t && t->valueType() && t->valueType()->pointer == 0 && t->valueType()->container) return; } const Variable *var = tok->variable(); if (var && var->nameToken() == tok) return; if (var && !var->isLocal()) return; // FIXME if (var && !var->isPointer()) { if (!var->isLocal() || var->isStatic()) return; } if (var && (Token::Match(var->nameToken(), "%name% [=:({)]") || var->isInit())) return; if (var && var->nameToken() == tok) return; // Are there unconditional assignment? if (var && Token::Match(var->nameToken(), "%varid% ;| %varid%| =", tok->varId())) return; // Arrays are allocated on the stack if (var && Token::Match(tok, "%var% [") && var->isArray()) return; if (tok->variable() && isVariableAssigned(tok->variable(), tok)) return; } // Uninitialized function argument bool inconclusive = false; if (Token::Match(tok->astParent(), "[,(]")) { const Token *parent = tok->astParent(); int count = 0; if (Token::simpleMatch(parent, ",")) { if (tok == parent->astOperand2()) count = 1; parent = parent->astParent(); while (Token::simpleMatch(parent, ",")) { count++; parent = parent->astParent(); } } if (Token::simpleMatch(parent, "(") && parent->astOperand1() != tok) { if (parent->astOperand1()->function()) { const Variable *argvar = parent->astOperand1()->function()->getArgumentVar(count); if (argvar && argvar->isReference() && !argvar->isConst()) return; if (uninitData && argvar && !argvar->isConst()) { if (parent->astOperand1()->function()->hasBody()) return; inconclusive = true; } if (!uninitStructMember.empty() && dataBase->isC() && argvar && !argvar->isConst()) { if (parent->astOperand1()->function()->hasBody()) return; inconclusive = true; } } else if (uninitData) { if (dataBase->settings->library.getFunction(parent->astOperand1())) return; if (parent->astOperand1()->isKeyword()) return; } } else if (uninitData) return; } if (inconclusive && !dataBase->settings->certainty.isEnabled(Certainty::inconclusive)) return; // Avoid FP for array declaration const Token *parent = tok->astParent(); while (parent && parent->str() == "[") parent = parent->astParent(); if (!parent) return; const std::string inconclusiveMessage(inconclusive ? ". It is inconclusive if there would be a problem in the function call." : ""); if (!uninitStructMember.empty()) { const std::string symbol = tok->expressionString() + "." + uninitStructMember; dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingUninitStructMember", "$symbol:" + symbol + "\nCannot determine that '$symbol' is initialized" + inconclusiveMessage, CWE_USE_OF_UNINITIALIZED_VARIABLE, inconclusive, value.type == ExprEngine::ValueType::BailoutValue); return; } std::string uninitexpr = tok->expressionString(); if (uninitData) uninitexpr += "[0]"; const std::string symbol = (tok->varId() > 0) ? ("$symbol:" + tok->str() + "\n") : std::string(); std::string constMessage; std::string errorId = "bughuntingUninit"; { const Token *vartok = tok; while (Token::Match(vartok, ".|[")) vartok = vartok->astOperand1(); const Variable *var = vartok ? vartok->variable() : nullptr; if (var && var->isArgument()) { errorId += "NonConstArg"; constMessage = " (you can use 'const' to say data must be initialized)"; } } dataBase->reportError(tok, Severity::SeverityType::error, errorId.c_str(), symbol + "Cannot determine that '" + uninitexpr + "' is initialized" + constMessage + inconclusiveMessage, CWE_USE_OF_UNINITIALIZED_VARIABLE, inconclusive, value.type == ExprEngine::ValueType::BailoutValue); } static void checkFunctionCall(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!Token::Match(tok->astParent(), "[(,]")) return; const Token *parent = tok->astParent(); while (Token::simpleMatch(parent, ",")) parent = parent->astParent(); if (!parent || parent->str() != "(") return; int num = 0; for (const Token *argTok: getArguments(parent->astOperand1())) { --num; if (argTok == tok) { num = -num; break; } } if (num <= 0) return; if (parent->astOperand1()->function()) { const Variable *arg = parent->astOperand1()->function()->getArgumentVar(num - 1); if (arg && arg->nameToken()) { std::string bad; MathLib::bigint low; if (arg->nameToken()->getCppcheckAttribute(TokenImpl::CppcheckAttributes::Type::LOW, &low)) { if (!(tok->hasKnownIntValue() && tok->getKnownIntValue() >= low) && value.isLessThan(dataBase, low)) bad = "__cppcheck_low__(" + std::to_string(low) + ")"; } MathLib::bigint high; if (arg->nameToken()->getCppcheckAttribute(TokenImpl::CppcheckAttributes::Type::HIGH, &high)) { if (!(tok->hasKnownIntValue() && tok->getKnownIntValue() <= high) && value.isGreaterThan(dataBase, high)) bad = "__cppcheck_high__(" + std::to_string(high) + ")"; } if (!bad.empty()) { dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingInvalidArgValue", "There is function call, cannot determine that " + std::to_string(num) + getOrdinalText(num) + " argument value meets the attribute " + bad, CWE(0), false); return; } } } // Check invalid function argument values.. for (const Library::InvalidArgValue &invalidArgValue : Library::getInvalidArgValues(dataBase->settings->library.validarg(parent->astOperand1(), num))) { bool err = false; std::string bad; switch (invalidArgValue.type) { case Library::InvalidArgValue::Type::eq: if (!tok->hasKnownIntValue() || tok->getKnownIntValue() == MathLib::toLongNumber(invalidArgValue.op1)) err = value.isEqual(dataBase, MathLib::toLongNumber(invalidArgValue.op1)); bad = "equals " + invalidArgValue.op1; break; case Library::InvalidArgValue::Type::le: if (!tok->hasKnownIntValue() || tok->getKnownIntValue() <= MathLib::toLongNumber(invalidArgValue.op1)) err = value.isLessThan(dataBase, MathLib::toLongNumber(invalidArgValue.op1) + 1); bad = "less equal " + invalidArgValue.op1; break; case Library::InvalidArgValue::Type::lt: if (!tok->hasKnownIntValue() || tok->getKnownIntValue() < MathLib::toLongNumber(invalidArgValue.op1)) err = value.isLessThan(dataBase, MathLib::toLongNumber(invalidArgValue.op1)); bad = "less than " + invalidArgValue.op1; break; case Library::InvalidArgValue::Type::ge: if (!tok->hasKnownIntValue() || tok->getKnownIntValue() >= MathLib::toLongNumber(invalidArgValue.op1)) err = value.isGreaterThan(dataBase, MathLib::toLongNumber(invalidArgValue.op1) - 1); bad = "greater equal " + invalidArgValue.op1; break; case Library::InvalidArgValue::Type::gt: if (!tok->hasKnownIntValue() || tok->getKnownIntValue() > MathLib::toLongNumber(invalidArgValue.op1)) err = value.isGreaterThan(dataBase, MathLib::toLongNumber(invalidArgValue.op1)); bad = "greater than " + invalidArgValue.op1; break; case Library::InvalidArgValue::Type::range: // TODO err = value.isEqual(dataBase, MathLib::toLongNumber(invalidArgValue.op1)); err |= value.isEqual(dataBase, MathLib::toLongNumber(invalidArgValue.op2)); bad = "range " + invalidArgValue.op1 + "-" + invalidArgValue.op2; break; } if (err) { dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingInvalidArgValue", "There is function call, cannot determine that " + std::to_string(num) + getOrdinalText(num) + " argument value is valid. Bad value: " + bad, CWE(0), false); break; } } // Uninitialized function argument.. if (dataBase->settings->library.isuninitargbad(parent->astOperand1(), num) && dataBase->settings->library.isnullargbad(parent->astOperand1(), num) && value.type == ExprEngine::ValueType::ArrayValue) { const ExprEngine::ArrayValue &arrayValue = static_cast(value); auto index0 = std::make_shared("0", 0, 0); for (const auto &v: arrayValue.read(index0)) { if (v.second->isUninit(dataBase)) { dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingUninitArg", "There is function call, cannot determine that " + std::to_string(num) + getOrdinalText(num) + " argument is initialized.", CWE_USE_OF_UNINITIALIZED_VARIABLE, false); break; } } } } static void checkAssignment(const Token *tok, const ExprEngine::Value &value, ExprEngine::DataBase *dataBase) { if (!Token::simpleMatch(tok->astParent(), "=")) return; const Token *lhs = tok->astParent()->astOperand1(); while (Token::simpleMatch(lhs, ".")) lhs = lhs->astOperand2(); if (!lhs || !lhs->variable() || !lhs->variable()->nameToken()) return; const Token *vartok = lhs->variable()->nameToken(); bool executable = false; std::string fullName = lhs->variable()->name(); for (const Scope *s = lhs->variable()->nameToken()->scope(); s->type != Scope::ScopeType::eGlobal; s = s->nestedIn) { if (s->isExecutable()) { executable = true; break; } fullName = s->className + "::" + fullName; } auto getMinMaxValue = [=](TokenImpl::CppcheckAttributes::Type type, MathLib::bigint *val) { if (vartok->getCppcheckAttribute(type, val)) return true; if (!executable) { const auto it = dataBase->settings->variableContracts.find(fullName); if (it != dataBase->settings->variableContracts.end()) { const std::string *str; if (type == TokenImpl::CppcheckAttributes::Type::LOW) str = &it->second.minValue; else if (type == TokenImpl::CppcheckAttributes::Type::HIGH) str = &it->second.maxValue; else return false; *val = MathLib::toLongNumber(*str); return !str->empty(); } } return false; }; MathLib::bigint low; if (getMinMaxValue(TokenImpl::CppcheckAttributes::Type::LOW, &low)) { if (value.isLessThan(dataBase, low)) dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingAssign", "There is assignment, cannot determine that value is greater or equal with " + std::to_string(low), CWE_INCORRECT_CALCULATION, false); } MathLib::bigint high; if (getMinMaxValue(TokenImpl::CppcheckAttributes::Type::HIGH, &high)) { if (value.isGreaterThan(dataBase, high)) dataBase->reportError(tok, Severity::SeverityType::error, "bughuntingAssign", "There is assignment, cannot determine that value is lower or equal with " + std::to_string(high), CWE_INCORRECT_CALCULATION, false); } } void addBughuntingChecks(std::vector *callbacks) { callbacks->push_back(arrayIndex); callbacks->push_back(bufferOverflow); callbacks->push_back(divByZero); callbacks->push_back(checkFunctionCall); callbacks->push_back(checkAssignment); #ifdef BUG_HUNTING_INTEGEROVERFLOW callbacks->push_back(integerOverflow); #endif callbacks->push_back(uninit); }