/* * Cppcheck - A tool for static C/C++ code analysis * Copyright (C) 2007-2019 Cppcheck team. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ //--------------------------------------------------------------------------- #include "checkuninitvar.h" #include "astutils.h" #include "checknullpointer.h" // CheckNullPointer::isPointerDeref #include "errorlogger.h" #include "library.h" #include "mathlib.h" #include "settings.h" #include "symboldatabase.h" #include "token.h" #include "tokenize.h" #include "valueflow.h" #include #include #include #include #include #include #include //--------------------------------------------------------------------------- // Register this check class (by creating a static instance of it) namespace { CheckUninitVar instance; } //--------------------------------------------------------------------------- // CWE ids used: static const struct CWE CWE476(476U); // NULL Pointer Dereference static const struct CWE CWE676(676U); static const struct CWE CWE908(908U); static const struct CWE CWE825(825U); // get ast parent, skip possible address-of and casts static const Token *getAstParentSkipPossibleCastAndAddressOf(const Token *vartok, bool *unknown) { if (unknown) *unknown = false; if (!vartok) return nullptr; const Token *parent = vartok->astParent(); while (Token::Match(parent, ".|::")) parent = parent->astParent(); if (!parent) return nullptr; if (parent->isUnaryOp("&")) parent = parent->astParent(); else if (parent->str() == "&" && vartok == parent->astOperand2() && Token::Match(parent->astOperand1()->previous(), "( %type% )")) { parent = parent->astParent(); if (unknown) *unknown = true; } while (parent && parent->isCast()) parent = parent->astParent(); return parent; } void CheckUninitVar::check() { const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); std::set arrayTypeDefs; for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (Token::Match(tok, "%name% [") && tok->variable() && Token::Match(tok->variable()->typeStartToken(), "%type% %var% ;")) arrayTypeDefs.insert(tok->variable()->typeStartToken()->str()); } // check every executable scope for (const Scope &scope : symbolDatabase->scopeList) { if (scope.isExecutable()) { checkScope(&scope, arrayTypeDefs); } } } void CheckUninitVar::checkScope(const Scope* scope, const std::set &arrayTypeDefs) { for (const Variable &var : scope->varlist) { if ((mTokenizer->isCPP() && var.type() && !var.isPointer() && var.type()->needInitialization != Type::True) || var.isStatic() || var.isExtern() || var.isReference()) continue; // don't warn for try/catch exception variable if (var.isThrow()) continue; if (Token::Match(var.nameToken()->next(), "[({:]")) continue; if (Token::Match(var.nameToken(), "%name% =")) { // Variable is initialized, but Rhs might be not checkRhs(var.nameToken(), var, NO_ALLOC, 0U, emptyString); continue; } if (Token::Match(var.nameToken(), "%name% ) (") && Token::simpleMatch(var.nameToken()->linkAt(2), ") =")) { // Function pointer is initialized, but Rhs might be not checkRhs(var.nameToken()->linkAt(2)->next(), var, NO_ALLOC, 0U, emptyString); continue; } if (var.isArray() || var.isPointerToArray()) { const Token *tok = var.nameToken()->next(); if (var.isPointerToArray()) tok = tok->next(); while (Token::simpleMatch(tok->link(), "] [")) tok = tok->link()->next(); if (Token::Match(tok->link(), "] =|{")) continue; } bool stdtype = mTokenizer->isC() && arrayTypeDefs.find(var.typeStartToken()->str()) == arrayTypeDefs.end(); const Token* tok = var.typeStartToken(); for (; tok != var.nameToken() && tok->str() != "<"; tok = tok->next()) { if (tok->isStandardType() || tok->isEnumType()) stdtype = true; } if (var.isArray() && !stdtype) continue; while (tok && tok->str() != ";") tok = tok->next(); if (!tok) continue; if (tok->astParent() && Token::simpleMatch(tok->astParent()->previous(), "for (") && checkLoopBody(tok->astParent()->link()->next(), var, var.isArray() ? ARRAY : NO_ALLOC, emptyString, true)) continue; if (var.isArray()) { Alloc alloc = ARRAY; const std::map variableValue; checkScopeForVariable(tok, var, nullptr, nullptr, &alloc, emptyString, variableValue); continue; } if (stdtype || var.isPointer()) { Alloc alloc = NO_ALLOC; const std::map variableValue; checkScopeForVariable(tok, var, nullptr, nullptr, &alloc, emptyString, variableValue); } if (var.type()) checkStruct(tok, var); } if (scope->function) { for (const Variable &arg : scope->function->argumentList) { if (arg.declarationId() && Token::Match(arg.typeStartToken(), "%type% * %name% [,)]")) { // Treat the pointer as initialized until it is assigned by malloc for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "[;{}] %varid% = %name% (", arg.declarationId()) && mSettings->library.returnuninitdata.count(tok->strAt(3)) == 1U) { if (arg.typeStartToken()->strAt(-1) == "struct" || (arg.type() && arg.type()->isStructType())) checkStruct(tok, arg); else if (arg.typeStartToken()->isStandardType() || arg.typeStartToken()->isEnumType()) { Alloc alloc = NO_ALLOC; const std::map variableValue; checkScopeForVariable(tok->next(), arg, nullptr, nullptr, &alloc, emptyString, variableValue); } } } } } } } void CheckUninitVar::checkStruct(const Token *tok, const Variable &structvar) { const Token *typeToken = structvar.typeStartToken(); const SymbolDatabase * symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope *scope2 : symbolDatabase->classAndStructScopes) { if (scope2->className == typeToken->str() && scope2->numConstructors == 0U) { for (const Variable &var : scope2->varlist) { if (var.isStatic() || var.hasDefault() || var.isArray() || (!mTokenizer->isC() && var.isClass() && (!var.type() || var.type()->needInitialization != Type::True))) continue; // is the variable declared in a inner union? bool innerunion = false; for (const Scope *innerScope : scope2->nestedList) { if (innerScope->type == Scope::eUnion) { if (var.typeStartToken()->linenr() >= innerScope->bodyStart->linenr() && var.typeStartToken()->linenr() <= innerScope->bodyEnd->linenr()) { innerunion = true; break; } } } if (!innerunion) { Alloc alloc = NO_ALLOC; const Token *tok2 = tok; if (tok->str() == "}") tok2 = tok2->next(); const std::map variableValue; checkScopeForVariable(tok2, structvar, nullptr, nullptr, &alloc, var.name(), variableValue); } } } } } static VariableValue operator!(VariableValue v) { v.notEqual = !v.notEqual; return v; } static bool operator==(const VariableValue & v, MathLib::bigint i) { return v.notEqual ? (i != v.value) : (i == v.value); } static bool operator!=(const VariableValue & v, MathLib::bigint i) { return v.notEqual ? (i == v.value) : (i != v.value); } static void conditionAlwaysTrueOrFalse(const Token *tok, const std::map &variableValue, bool *alwaysTrue, bool *alwaysFalse) { if (!tok) return; if (tok->isName() || tok->str() == ".") { while (tok && tok->str() == ".") tok = tok->astOperand2(); const std::map::const_iterator it = variableValue.find(tok ? tok->varId() : ~0U); if (it != variableValue.end()) { *alwaysTrue = (it->second != 0LL); *alwaysFalse = (it->second == 0LL); } } else if (tok->isComparisonOp()) { if (tok->hasKnownIntValue()) { if (tok->values().front().intvalue) *alwaysTrue = true; else *alwaysFalse = true; return; } const Token *vartok, *numtok; if (tok->astOperand2() && tok->astOperand2()->isNumber()) { vartok = tok->astOperand1(); numtok = tok->astOperand2(); } else if (tok->astOperand1() && tok->astOperand1()->isNumber()) { vartok = tok->astOperand2(); numtok = tok->astOperand1(); } else { return; } while (vartok && vartok->str() == ".") vartok = vartok->astOperand2(); const std::map::const_iterator it = variableValue.find(vartok ? vartok->varId() : ~0U); if (it == variableValue.end()) return; if (tok->str() == "==") *alwaysTrue = (it->second == MathLib::toLongNumber(numtok->str())); else if (tok->str() == "!=") *alwaysTrue = (it->second != MathLib::toLongNumber(numtok->str())); else return; *alwaysFalse = !(*alwaysTrue); } else if (tok->str() == "!") { bool t=false,f=false; conditionAlwaysTrueOrFalse(tok->astOperand1(), variableValue, &t, &f); if (t||f) { *alwaysTrue = !t; *alwaysFalse = !f; } } else if (tok->str() == "||") { bool t1=false, f1=false; conditionAlwaysTrueOrFalse(tok->astOperand1(), variableValue, &t1, &f1); bool t2=false, f2=false; if (!t1) conditionAlwaysTrueOrFalse(tok->astOperand2(), variableValue, &t2, &f2); *alwaysTrue = (t1 || t2); *alwaysFalse = (f1 && f2); } else if (tok->str() == "&&") { bool t1=false, f1=false; conditionAlwaysTrueOrFalse(tok->astOperand1(), variableValue, &t1, &f1); bool t2=false, f2=false; if (!f1) conditionAlwaysTrueOrFalse(tok->astOperand2(), variableValue, &t2, &f2); *alwaysTrue = (t1 && t2); *alwaysFalse = (f1 || f2); } } static bool isVariableUsed(const Token *tok, const Variable& var) { if (!tok) return false; if (tok->str() == "&" && !tok->astOperand2()) return false; if (tok->isConstOp()) return isVariableUsed(tok->astOperand1(),var) || isVariableUsed(tok->astOperand2(),var); if (tok->varId() != var.declarationId()) return false; if (!var.isArray()) return true; const Token *parent = tok->astParent(); while (Token::Match(parent, "[?:]")) parent = parent->astParent(); // no dereference, then array is not "used" if (!Token::Match(parent, "*|[")) return false; const Token *parent2 = parent->astParent(); // TODO: handle function calls. There is a TODO assertion in TestUninitVar::uninitvar_arrays return !parent2 || parent2->isConstOp() || (parent2->str() == "=" && parent2->astOperand2() == parent); } bool CheckUninitVar::checkScopeForVariable(const Token *tok, const Variable& var, bool * const possibleInit, bool * const noreturn, Alloc* const alloc, const std::string &membervar, std::map variableValue) { const bool suppressErrors(possibleInit && *possibleInit); // Assume that this is a variable delaratkon, rather than a fundef const bool printDebug = mSettings->debugwarnings; if (possibleInit) *possibleInit = false; unsigned int number_of_if = 0; if (var.declarationId() == 0U) return true; for (; tok; tok = tok->next()) { // End of scope.. if (tok->str() == "}") { if (number_of_if && possibleInit) *possibleInit = true; // might be a noreturn function.. if (mTokenizer->IsScopeNoReturn(tok)) { if (noreturn) *noreturn = true; return false; } break; } // Unconditional inner scope or try.. if (tok->str() == "{" && Token::Match(tok->previous(), ",|;|{|}|try")) { if (checkScopeForVariable(tok->next(), var, possibleInit, noreturn, alloc, membervar, variableValue)) return true; tok = tok->link(); continue; } // assignment with nonzero constant.. if (Token::Match(tok->previous(), "[;{}] %var% = - %name% ;")) variableValue[tok->varId()] = !VariableValue(0); // Inner scope.. else if (Token::simpleMatch(tok, "if (")) { bool alwaysTrue = false; bool alwaysFalse = false; // Is variable assigned in condition? if (!membervar.empty()) { for (const Token *cond = tok->linkAt(1); cond != tok; cond = cond->previous()) { if (cond->varId() == var.declarationId() && isMemberVariableAssignment(cond, membervar)) return true; } } conditionAlwaysTrueOrFalse(tok->next()->astOperand2(), variableValue, &alwaysTrue, &alwaysFalse); // initialization / usage in condition.. if (!alwaysTrue && checkIfForWhileHead(tok->next(), var, suppressErrors, bool(number_of_if == 0), *alloc, membervar)) return true; // checking if a not-zero variable is zero => bail out unsigned int condVarId = 0; VariableValue condVarValue(0); const Token *condVarTok = nullptr; if (alwaysFalse) ; else if (Token::simpleMatch(tok, "if (") && astIsVariableComparison(tok->next()->astOperand2(), "!=", "0", &condVarTok)) { const std::map::const_iterator it = variableValue.find(condVarTok->varId()); if (it != variableValue.end() && it->second != 0) return true; // this scope is not fully analysed => return true else { condVarId = condVarTok->varId(); condVarValue = !VariableValue(0); } } else if (Token::simpleMatch(tok, "if (") && Token::Match(tok->next()->astOperand2(), "==|!=")) { const Token *condition = tok->next()->astOperand2(); const Token *lhs = condition->astOperand1(); const Token *rhs = condition->astOperand2(); const Token *vartok = rhs && rhs->isNumber() ? lhs : rhs; const Token *numtok = rhs && rhs->isNumber() ? rhs : lhs; while (Token::simpleMatch(vartok, ".")) vartok = vartok->astOperand2(); if (vartok && vartok->varId() && numtok) { const std::map::const_iterator it = variableValue.find(vartok->varId()); if (it != variableValue.end() && it->second != MathLib::toLongNumber(numtok->str())) return true; // this scope is not fully analysed => return true else { condVarId = vartok->varId(); condVarValue = VariableValue(MathLib::toLongNumber(numtok->str())); if (condition->str() == "!=") condVarValue = !condVarValue; } } } // goto the { tok = tok->next()->link()->next(); if (!tok) break; if (tok->str() == "{") { bool possibleInitIf((!alwaysTrue && number_of_if > 0) || suppressErrors); bool noreturnIf = false; const bool initif = !alwaysFalse && checkScopeForVariable(tok->next(), var, &possibleInitIf, &noreturnIf, alloc, membervar, variableValue); // bail out for such code: // if (a) x=0; // conditional initialization // if (b) return; // cppcheck doesn't know if b can be false when a is false. // x++; // it's possible x is always initialized if (!alwaysTrue && noreturnIf && number_of_if > 0) { if (printDebug) { std::string condition; for (const Token *tok2 = tok->linkAt(-1); tok2 != tok; tok2 = tok2->next()) { condition += tok2->str(); if (tok2->isName() && tok2->next()->isName()) condition += ' '; } reportError(tok, Severity::debug, "debug", "bailout uninitialized variable checking for '" + var.name() + "'. can't determine if this condition can be false when previous condition is false: " + condition); } return true; } if (alwaysTrue && (initif || noreturnIf)) return true; std::map varValueIf; if (!alwaysFalse && !initif && !noreturnIf) { for (const Token *tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) { if (Token::Match(tok2, "[;{}.] %name% = - %name% ;")) varValueIf[tok2->next()->varId()] = !VariableValue(0); else if (Token::Match(tok2, "[;{}.] %name% = %num% ;")) varValueIf[tok2->next()->varId()] = VariableValue(MathLib::toLongNumber(tok2->strAt(3))); } } if (initif && condVarId > 0U) variableValue[condVarId] = !condVarValue; // goto the } tok = tok->link(); if (!Token::simpleMatch(tok, "} else {")) { if (initif || possibleInitIf) { ++number_of_if; if (number_of_if >= 2) return true; } } else { // goto the { tok = tok->tokAt(2); bool possibleInitElse((!alwaysFalse && number_of_if > 0) || suppressErrors); bool noreturnElse = false; const bool initelse = !alwaysTrue && checkScopeForVariable(tok->next(), var, &possibleInitElse, &noreturnElse, alloc, membervar, variableValue); std::map varValueElse; if (!alwaysTrue && !initelse && !noreturnElse) { for (const Token *tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) { if (Token::Match(tok2, "[;{}.] %var% = - %name% ;")) varValueElse[tok2->next()->varId()] = !VariableValue(0); else if (Token::Match(tok2, "[;{}.] %var% = %num% ;")) varValueElse[tok2->next()->varId()] = VariableValue(MathLib::toLongNumber(tok2->strAt(3))); } } if (initelse && condVarId > 0U && !noreturnIf && !noreturnElse) variableValue[condVarId] = condVarValue; // goto the } tok = tok->link(); if ((alwaysFalse || initif || noreturnIf) && (alwaysTrue || initelse || noreturnElse)) return true; if (initif || initelse || possibleInitElse) ++number_of_if; if (!initif && !noreturnIf) variableValue.insert(varValueIf.begin(), varValueIf.end()); if (!initelse && !noreturnElse) variableValue.insert(varValueElse.begin(), varValueElse.end()); } } } // = { .. } else if (Token::simpleMatch(tok, "= {")) { // end token const Token *end = tok->next()->link(); // If address of variable is taken in the block then bail out if (var.isPointer() || var.isArray()) { if (Token::findmatch(tok->tokAt(2), "%varid%", end, var.declarationId())) return true; } else if (Token::findmatch(tok->tokAt(2), "& %varid%", end, var.declarationId())) { return true; } // Skip block tok = end; continue; } // skip sizeof / offsetof if (Token::Match(tok, "sizeof|typeof|offsetof|decltype (")) tok = tok->next()->link(); // for/while.. else if (Token::Match(tok, "for|while (") || Token::simpleMatch(tok, "do {")) { const bool forwhile = Token::Match(tok, "for|while ("); // is variable initialized in for-head? if (forwhile && checkIfForWhileHead(tok->next(), var, tok->str() == "for", false, *alloc, membervar)) return true; // goto the { const Token *tok2 = forwhile ? tok->next()->link()->next() : tok->next(); if (tok2 && tok2->str() == "{") { const bool init = checkLoopBody(tok2, var, *alloc, membervar, (number_of_if > 0) || suppressErrors); // variable is initialized in the loop.. if (init) return true; // is variable used in for-head? bool initcond = false; if (!suppressErrors) { const Token *startCond = forwhile ? tok->next() : tok->next()->link()->tokAt(2); initcond = checkIfForWhileHead(startCond, var, false, bool(number_of_if == 0), *alloc, membervar); } // goto "}" tok = tok2->link(); // do-while => goto ")" if (!forwhile) { // Assert that the tokens are '} while (' if (!Token::simpleMatch(tok, "} while (")) { if (printDebug) reportError(tok,Severity::debug,"","assertion failed '} while ('"); break; } // Goto ')' tok = tok->linkAt(2); if (!tok) // bailout : invalid code / bad tokenizer break; if (initcond) // variable is initialized in while-condition return true; } } } // Unknown or unhandled inner scope else if (Token::simpleMatch(tok, ") {") || (Token::Match(tok, "%name% {") && tok->str() != "try")) { if (tok->str() == "struct" || tok->str() == "union") { tok = tok->linkAt(1); continue; } return true; } // bailout if there is ({ if (Token::simpleMatch(tok, "( {")) { return true; } // bailout if there is assembler code or setjmp if (Token::Match(tok, "asm|setjmp (")) { return true; } // bailout if there is a goto label if (Token::Match(tok, "[;{}] %name% :")) { return true; } if (tok->str() == "?") { if (!tok->astOperand2()) return true; const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var); const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var); const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0); if (err) uninitvarError(tok, var.nameToken()->str(), *alloc); // Todo: skip expression if there is no error return true; } if (Token::Match(tok, "return|break|continue|throw|goto")) { if (noreturn) *noreturn = true; tok = tok->next(); while (tok && tok->str() != ";") { // variable is seen.. if (tok->varId() == var.declarationId()) { if (!membervar.empty()) { if (!suppressErrors && Token::Match(tok, "%name% . %name% ;|%cop%") && tok->strAt(2) == membervar) uninitStructMemberError(tok, tok->str() + "." + membervar); } // Use variable else if (!suppressErrors && isVariableUsage(tok, var.isPointer(), *alloc)) uninitvarError(tok, tok->str(), *alloc); return true; } else if (Token::Match(tok, "sizeof|typeof|offsetof|decltype (")) tok = tok->linkAt(1); else if (tok->str() == "?") { if (!tok->astOperand2()) return true; const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var); const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var); const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0); if (err) uninitvarError(tok, var.nameToken()->str(), *alloc); return true; } tok = tok->next(); } return (noreturn == nullptr); } // variable is seen.. if (tok->varId() == var.declarationId()) { // calling function that returns uninit data through pointer.. if (var.isPointer() && Token::simpleMatch(tok->next(), "=")) { const Token *rhs = tok->next()->astOperand2(); while (rhs && rhs->isCast()) rhs = rhs->astOperand1(); if (rhs && Token::Match(rhs->previous(), "%name% (") && mSettings->library.returnuninitdata.count(rhs->previous()->str()) > 0U) { *alloc = NO_CTOR_CALL; continue; } } if (var.isPointer() && (var.typeStartToken()->isStandardType() || var.typeStartToken()->isEnumType() || (var.type() && var.type()->needInitialization == Type::True)) && Token::simpleMatch(tok->next(), "= new")) { *alloc = CTOR_CALL; // type has constructor(s) if (var.typeScope() && var.typeScope()->numConstructors > 0) return true; // standard or enum type: check if new initializes the allocated memory if (var.typeStartToken()->isStandardType() || var.typeStartToken()->isEnumType()) { // scalar new with initialization if (Token::Match(tok->next(), "= new %type% (")) return true; // array new if (Token::Match(tok->next(), "= new %type% [")) { const Token* tokClosingBracket=tok->linkAt(4); // array new with initialization if (tokClosingBracket && Token::simpleMatch(tokClosingBracket->next(), "( )")) return true; } } continue; } if (!membervar.empty()) { if (isMemberVariableAssignment(tok, membervar)) { checkRhs(tok, var, *alloc, number_of_if, membervar); return true; } if (isMemberVariableUsage(tok, var.isPointer(), *alloc, membervar)) { uninitStructMemberError(tok, tok->str() + "." + membervar); return true; } else if (Token::Match(tok->previous(), "[(,] %name% [,)]")) return true; } else { // Use variable if (!suppressErrors && isVariableUsage(tok, var.isPointer(), *alloc)) { uninitvarError(tok, tok->str(), *alloc); return true; } else { if (tok->strAt(1) == "=") checkRhs(tok, var, *alloc, number_of_if, emptyString); // assume that variable is assigned return true; } } } } return false; } bool CheckUninitVar::checkIfForWhileHead(const Token *startparentheses, const Variable& var, bool suppressErrors, bool isuninit, Alloc alloc, const std::string &membervar) { const Token * const endpar = startparentheses->link(); if (Token::Match(startparentheses, "( ! %name% %oror%") && startparentheses->tokAt(2)->getValue(0)) suppressErrors = true; for (const Token *tok = startparentheses->next(); tok && tok != endpar; tok = tok->next()) { if (tok->varId() == var.declarationId()) { if (Token::Match(tok, "%name% . %name%")) { if (membervar.empty()) return true; if (tok->strAt(2) == membervar) { if (isMemberVariableAssignment(tok, membervar)) return true; if (!suppressErrors && isMemberVariableUsage(tok, var.isPointer(), alloc, membervar)) uninitStructMemberError(tok, tok->str() + "." + membervar); } continue; } if (isVariableUsage(tok, var.isPointer(), alloc)) { if (suppressErrors) continue; uninitvarError(tok, tok->str(), alloc); } return true; } if (Token::Match(tok, "sizeof|decltype|offsetof (")) tok = tok->next()->link(); if ((!isuninit || !membervar.empty()) && tok->str() == "&&") suppressErrors = true; } return false; } bool CheckUninitVar::checkLoopBody(const Token *tok, const Variable& var, const Alloc alloc, const std::string &membervar, const bool suppressErrors) { const Token *usetok = nullptr; assert(tok->str() == "{"); for (const Token * const end = tok->link(); tok != end; tok = tok->next()) { if (Token::Match(tok, "sizeof|typeof (")) { tok = tok->next()->link(); continue; } if (Token::Match(tok, "asm ( %str% ) ;")) return true; if (tok->varId() != var.declarationId()) continue; if (!membervar.empty()) { if (isMemberVariableAssignment(tok, membervar)) { bool assign = true; bool rhs = false; // Used for tracking if an ")" is inner or outer const Token *rpar = nullptr; for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) { if (tok2->str() == "=") rhs = true; // Look at inner expressions but not outer expressions if (!rpar && tok2->str() == "(") rpar = tok2->link(); else if (tok2->str() == ")") { // No rpar => this is an outer right parenthesis if (!rpar) break; if (rpar == tok2) rpar = nullptr; } if (tok2->str() == ";" || (!rpar && tok2->str() == ",")) break; if (rhs && tok2->varId() == var.declarationId() && isMemberVariableUsage(tok2, var.isPointer(), alloc, membervar)) { assign = false; break; } } if (assign) return true; } if (isMemberVariableUsage(tok, var.isPointer(), alloc, membervar)) usetok = tok; else if (Token::Match(tok->previous(), "[(,] %name% [,)]")) return true; } else { if (isVariableUsage(tok, var.isPointer(), alloc)) usetok = tok; else if (tok->strAt(1) == "=") { // Is var used in rhs? bool rhs = false; std::stack tokens; tokens.push(tok->next()->astOperand2()); while (!tokens.empty()) { const Token *t = tokens.top(); tokens.pop(); if (!t) continue; if (t->varId() == var.declarationId()) { // var is used in rhs rhs = true; break; } if (Token::simpleMatch(t->previous(),"sizeof (")) continue; tokens.push(t->astOperand1()); tokens.push(t->astOperand2()); } if (!rhs) return true; } else { return true; } } } if (!suppressErrors && usetok) { if (membervar.empty()) uninitvarError(usetok, usetok->str(), alloc); else uninitStructMemberError(usetok, usetok->str() + "." + membervar); return true; } return false; } void CheckUninitVar::checkRhs(const Token *tok, const Variable &var, Alloc alloc, unsigned int number_of_if, const std::string &membervar) { bool rhs = false; unsigned int indent = 0; while (nullptr != (tok = tok->next())) { if (tok->str() == "=") rhs = true; else if (rhs && tok->varId() == var.declarationId()) { if (membervar.empty() && isVariableUsage(tok, var.isPointer(), alloc)) uninitvarError(tok, tok->str(), alloc); else if (!membervar.empty() && isMemberVariableUsage(tok, var.isPointer(), alloc, membervar)) uninitStructMemberError(tok, tok->str() + "." + membervar); else if (Token::Match(tok, "%var% =")) break; } else if (tok->str() == ";" || (indent==0 && tok->str() == ",")) break; else if (tok->str() == "(") ++indent; else if (tok->str() == ")") { if (indent == 0) break; --indent; } else if (tok->str() == "?" && tok->astOperand2()) { const bool used1 = isVariableUsed(tok->astOperand2()->astOperand1(), var); const bool used0 = isVariableUsed(tok->astOperand2()->astOperand2(), var); const bool err = (number_of_if == 0) ? (used1 || used0) : (used1 && used0); if (err) uninitvarError(tok, var.nameToken()->str(), alloc); break; } else if (Token::simpleMatch(tok, "sizeof (")) tok = tok->next()->link(); } } bool CheckUninitVar::isVariableUsage(const Token *vartok, bool pointer, Alloc alloc) const { if (alloc == NO_ALLOC && ((Token::Match(vartok->previous(), "return|delete %var% !!=")) || (vartok->strAt(-1) == "]" && vartok->linkAt(-1)->strAt(-1) == "delete"))) return true; // Passing variable to typeof/__alignof__ if (Token::Match(vartok->tokAt(-3), "typeof|__alignof__ ( * %name%")) return false; // Accessing Rvalue member using "." or "->" if (Token::Match(vartok->previous(), "!!& %var% .")) { // Is struct member passed to function? if (!pointer) { // TODO: there are FN currently: // - should only return false if struct member is (or might be) array. // - should only return false if function argument is (or might be) non-const pointer or reference bool unknown = false; const Token *possibleParent = getAstParentSkipPossibleCastAndAddressOf(vartok, &unknown); if (Token::Match(possibleParent, "[(,]")) { if (unknown) return false; // TODO: output some info message? const int use = isFunctionParUsage(vartok, pointer, alloc); if (use >= 0) return (use>0); } } if (pointer && alloc != CTOR_CALL && Token::Match(vartok, "%name% . %name% (")) return true; bool assignment = false; const Token* parent = vartok->astParent(); while (parent) { if (parent->str() == "=") { assignment = true; break; } if (alloc != NO_ALLOC && parent->str() == "(") { if (!mSettings->library.isFunctionConst(parent->strAt(-1), true)) { assignment = true; break; } } parent = parent->astParent(); } if (!assignment) return true; } // Passing variable to function.. { bool unknown = false; const Token *possibleParent = getAstParentSkipPossibleCastAndAddressOf(vartok, &unknown); if (Token::Match(possibleParent, "[(,]")) { if (unknown) return false; // TODO: output some info message? const int use = isFunctionParUsage(vartok, pointer, alloc); if (use >= 0) return (use>0); } else if (!pointer && Token::simpleMatch(possibleParent, "=") && vartok->astParent()->str() == "&") { return false; } } if (Token::Match(vartok->previous(), "++|--|%cop%")) { if (mTokenizer->isCPP() && alloc == ARRAY && Token::Match(vartok->tokAt(-4), "& %var% =|( *")) return false; if (isLikelyStreamRead(mTokenizer->isCPP(), vartok->previous())) return false; if (mTokenizer->isCPP() && Token::simpleMatch(vartok->previous(), "<<")) { const Token* tok2 = vartok->previous(); // Looks like stream operator, but could also initialize the variable. Check lhs. do { tok2 = tok2->astOperand1(); } while (Token::simpleMatch(tok2, "<<")); if (tok2 && tok2->strAt(-1) == "::") tok2 = tok2->previous(); if (tok2 && (Token::simpleMatch(tok2->previous(), "std ::") || (tok2->variable() && tok2->variable()->isStlType()) || tok2->isStandardType() || tok2->isEnumType())) return true; const Variable *var = vartok->tokAt(-2)->variable(); return (var && (var->typeStartToken()->isStandardType() || var->typeStartToken()->isEnumType())); } // is there something like: ; "*((&var ..expr.. =" => the variable is assigned if (vartok->previous()->str() == "&" && !vartok->previous()->astOperand2()) return false; // bailout to avoid fp for 'int x = 2 + x();' where 'x()' is a unseen preprocessor macro (seen in linux) if (!pointer && vartok->next() && vartok->next()->str() == "(") return false; if (vartok->previous()->str() != "&" || !Token::Match(vartok->tokAt(-2), "[(,=?:]")) { if (alloc != NO_ALLOC && vartok->previous()->str() == "*") { // TestUninitVar::isVariableUsageDeref() const Token *parent = vartok->previous()->astParent(); if (parent && parent->str() == "=" && parent->astOperand1() == vartok->previous()) return false; if (vartok->variable() && vartok->variable()->dimensions().size() >= 2) return false; return true; } return alloc == NO_ALLOC; } } if (alloc == NO_ALLOC && Token::Match(vartok->previous(), "%assign% %name% %cop%|;|)")) { // taking reference? const Token *prev = vartok->tokAt(-2); while (Token::Match(prev, "%name%|*")) prev = prev->previous(); if (!Token::simpleMatch(prev, "&")) return true; } bool unknown = false; if (pointer && alloc == NO_ALLOC && CheckNullPointer::isPointerDeRef(vartok, unknown, mSettings)) { // function parameter? bool functionParameter = false; if (Token::Match(vartok->tokAt(-2), "%name% (") || vartok->previous()->str() == ",") functionParameter = true; // if this is not a function parameter report this dereference as variable usage if (!functionParameter) return true; } else if (alloc != NO_ALLOC && Token::Match(vartok, "%var% [")) { const Token *parent = vartok->next()->astParent(); while (Token::Match(parent, "[|.")) parent = parent->astParent(); if (Token::simpleMatch(parent, "&") && !parent->astOperand2()) return false; if (parent && Token::Match(parent->previous(), "if|while|switch (")) return true; if (Token::Match(parent, "[=,(]")) return false; return true; } if (mTokenizer->isCPP() && Token::simpleMatch(vartok->next(), "<<")) { // Is this calculation done in rhs? const Token *tok = vartok; while (Token::Match(tok, "%name%|.|::")) tok = tok->previous(); if (Token::Match(tok, "[;{}]")) return false; // Is variable a known POD type then this is a variable usage, // otherwise we assume it's not. return (vartok->valueType() && vartok->valueType()->isIntegral()); } if (alloc == NO_ALLOC && vartok->next() && vartok->next()->isOp() && !vartok->next()->isAssignmentOp()) return true; if (alloc == NO_ALLOC && vartok->next()->isAssignmentOp() && vartok->next()->str() != "=") return true; if (vartok->strAt(1) == "]") return true; return false; } /*** * Is function parameter "used" so a "usage of uninitialized variable" can * be written? If parameter is passed "by value" then it is "used". If it * is passed "by reference" then it is not necessarily "used". * @return -1 => unknown 0 => not used 1 => used */ int CheckUninitVar::isFunctionParUsage(const Token *vartok, bool pointer, Alloc alloc) const { bool unknown = false; const Token *parent = getAstParentSkipPossibleCastAndAddressOf(vartok, &unknown); if (unknown || !Token::Match(parent, "[(,]")) return -1; // locate start parentheses in function call.. unsigned int argumentNumber = 0; const Token *start = vartok; while (start && !Token::Match(start, "[;{}(]")) { if (start->str() == ")") start = start->link(); else if (start->str() == ",") ++argumentNumber; start = start->previous(); } if (!start) return -1; if (Token::simpleMatch(start->link(), ") {") && Token::Match(start->previous(), "if|for|while|switch")) return (!pointer || alloc == NO_ALLOC); // is this a function call? if (Token::Match(start->previous(), "%name% (")) { const bool address(vartok->previous()->str() == "&"); const bool array(vartok->variable() && vartok->variable()->isArray()); // check how function handle uninitialized data arguments.. const Function *func = start->previous()->function(); if (func) { const Variable *arg = func->getArgumentVar(argumentNumber); if (arg) { const Token *argStart = arg->typeStartToken(); if (!address && !array && Token::Match(argStart, "%type% %name%| [,)]")) return 1; if (pointer && !address && alloc == NO_ALLOC && Token::Match(argStart, "%type% * %name% [,)]")) return 1; while (argStart->previous() && argStart->previous()->isName()) argStart = argStart->previous(); if (Token::Match(argStart, "const %type% & %name% [,)]")) { // If it's a record it's ok to pass a partially uninitialized struct. if (vartok->variable() && vartok->variable()->valueType() && vartok->variable()->valueType()->type == ValueType::Type::RECORD) return -1; return 1; } if ((pointer || address) && alloc == NO_ALLOC && Token::Match(argStart, "const struct| %type% * %name% [,)]")) return 1; if ((pointer || address) && Token::Match(argStart, "const %type% %name% [") && Token::Match(argStart->linkAt(3), "] [,)]")) return 1; } } else if (Token::Match(start->previous(), "if|while|for")) { // control-flow statement reading the variable "by value" return alloc == NO_ALLOC; } else { const bool isnullbad = mSettings->library.isnullargbad(start->previous(), argumentNumber + 1); if (pointer && !address && isnullbad && alloc == NO_ALLOC) return 1; const bool isuninitbad = mSettings->library.isuninitargbad(start->previous(), argumentNumber + 1); if (alloc != NO_ALLOC) return isnullbad && isuninitbad; return isuninitbad && (!address || isnullbad); } } // unknown return -1; } bool CheckUninitVar::isMemberVariableAssignment(const Token *tok, const std::string &membervar) const { if (Token::Match(tok, "%name% . %name%") && tok->strAt(2) == membervar) { if (Token::Match(tok->tokAt(3), "[=.[]")) return true; else if (Token::Match(tok->tokAt(-2), "[(,=] &")) return true; else if (isLikelyStreamRead(mTokenizer->isCPP(), tok->previous())) return true; else if ((tok->previous() && tok->previous()->isConstOp()) || Token::Match(tok->previous(), "[|=")) ; // member variable usage else if (tok->tokAt(3)->isConstOp()) ; // member variable usage else if (Token::Match(tok->previous(), "[(,] %name% . %name% [,)]") && 1 == isFunctionParUsage(tok, false, NO_ALLOC)) { return false; } else return true; } else if (tok->strAt(1) == "=") return true; else if (Token::Match(tok, "%var% . %name% (")) { const Token *ftok = tok->tokAt(2); if (!ftok->function() || !ftok->function()->isConst()) // TODO: Try to determine if membervar is assigned in method return true; } else if (tok->strAt(-1) == "&") { if (Token::Match(tok->tokAt(-2), "[(,] & %name%")) { // locate start parentheses in function call.. unsigned int argumentNumber = 0; const Token *ftok = tok; while (ftok && !Token::Match(ftok, "[;{}(]")) { if (ftok->str() == ")") ftok = ftok->link(); else if (ftok->str() == ",") ++argumentNumber; ftok = ftok->previous(); } // is this a function call? ftok = ftok ? ftok->previous() : nullptr; if (Token::Match(ftok, "%name% (")) { // check how function handle uninitialized data arguments.. const Function *function = ftok->function(); const Variable *arg = function ? function->getArgumentVar(argumentNumber) : nullptr; const Token *argStart = arg ? arg->typeStartToken() : nullptr; while (argStart && argStart->previous() && argStart->previous()->isName()) argStart = argStart->previous(); if (Token::Match(argStart, "const struct| %type% * const| %name% [,)]")) return false; } else if (ftok && Token::simpleMatch(ftok->previous(), "= * (")) return false; } return true; } return false; } bool CheckUninitVar::isMemberVariableUsage(const Token *tok, bool isPointer, Alloc alloc, const std::string &membervar) const { if (Token::Match(tok->previous(), "[(,] %name% . %name% [,)]") && tok->strAt(2) == membervar) { const int use = isFunctionParUsage(tok, isPointer, alloc); if (use == 1) return true; } if (isMemberVariableAssignment(tok, membervar)) return false; if (Token::Match(tok, "%name% . %name%") && tok->strAt(2) == membervar && !(tok->tokAt(-2)->variable() && tok->tokAt(-2)->variable()->isReference())) return true; else if (!isPointer && Token::Match(tok->previous(), "[(,] %name% [,)]") && isVariableUsage(tok, isPointer, alloc)) return true; else if (!isPointer && Token::Match(tok->previous(), "= %name% ;")) return true; // = *(&var); else if (!isPointer && Token::simpleMatch(tok->astParent(),"&") && Token::simpleMatch(tok->astParent()->astParent(),"*") && Token::Match(tok->astParent()->astParent()->astParent(), "= * (| &") && tok->astParent()->astParent()->astParent()->astOperand2() == tok->astParent()->astParent()) return true; else if (mSettings->experimental && !isPointer && Token::Match(tok->tokAt(-2), "[(,] & %name% [,)]") && isVariableUsage(tok, isPointer, alloc)) return true; return false; } void CheckUninitVar::uninitstringError(const Token *tok, const std::string &varname, bool strncpy_) { reportError(tok, Severity::error, "uninitstring", "$symbol:" + varname + "\nDangerous usage of '$symbol'" + (strncpy_ ? " (strncpy doesn't always null-terminate it)." : " (not null-terminated)."), CWE676, false); } void CheckUninitVar::uninitdataError(const Token *tok, const std::string &varname) { reportError(tok, Severity::error, "uninitdata", "$symbol:" + varname + "\nMemory is allocated but not initialized: $symbol", CWE908, false); } void CheckUninitVar::uninitvarError(const Token *tok, const std::string &varname) { reportError(tok, Severity::error, "uninitvar", "$symbol:" + varname + "\nUninitialized variable: $symbol", CWE908, false); } void CheckUninitVar::uninitStructMemberError(const Token *tok, const std::string &membername) { reportError(tok, Severity::error, "uninitStructMember", "$symbol:" + membername + "\nUninitialized struct member: $symbol", CWE908, false); } void CheckUninitVar::valueFlowUninit() { const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); // check every executable scope for (const Scope &scope : symbolDatabase->scopeList) { if (!scope.isExecutable()) continue; for (const Token* tok = scope.bodyStart; tok != scope.bodyEnd; tok = tok->next()) { if (Token::simpleMatch(tok, "sizeof (")) { tok = tok->linkAt(1); continue; } if (!tok->variable() || tok->values().size() != 1U) continue; const ValueFlow::Value &v = tok->values().front(); if (v.valueType != ValueFlow::Value::UNINIT || v.isInconclusive()) continue; if (!isVariableUsage(tok, tok->variable()->isPointer(), NO_ALLOC)) continue; uninitvarError(tok, tok->str()); } } } void CheckUninitVar::deadPointer() { const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); // check every executable scope for (const Scope &scope : symbolDatabase->scopeList) { if (!scope.isExecutable()) continue; // Dead pointers.. for (const Token* tok = scope.bodyStart; tok != scope.bodyEnd; tok = tok->next()) { if (tok->variable() && tok->variable()->isPointer() && isVariableUsage(tok, true, NO_ALLOC)) { const Token *alias = tok->getValueTokenDeadPointer(); if (alias) { deadPointerError(tok,alias); } } } } } void CheckUninitVar::deadPointerError(const Token *pointer, const Token *alias) { const std::string strpointer(pointer ? pointer->str() : std::string("pointer")); const std::string stralias(alias ? alias->expressionString() : std::string("&x")); reportError(pointer, Severity::error, "deadpointer", "$symbol:" + strpointer + "\nDead pointer usage. Pointer '$symbol' is dead if it has been assigned '" + stralias + "' at line " + MathLib::toString(alias ? alias->linenr() : 0U) + ".", CWE825, false); } std::string CheckUninitVar::MyFileInfo::toString() const { return CTU::toString(unsafeUsage); } Check::FileInfo *CheckUninitVar::getFileInfo(const Tokenizer *tokenizer, const Settings *settings) const { const CheckUninitVar checker(tokenizer, settings, nullptr); return checker.getFileInfo(); } static bool isVariableUsage(const Check *check, const Token *vartok) { const CheckUninitVar *c = dynamic_cast(check); return c && c->isVariableUsage(vartok, true, CheckUninitVar::Alloc::ARRAY); } Check::FileInfo *CheckUninitVar::getFileInfo() const { const std::list &unsafeUsage = CTU::getUnsafeUsage(mTokenizer, mSettings, this, ::isVariableUsage); if (unsafeUsage.empty()) return nullptr; MyFileInfo *fileInfo = new MyFileInfo; fileInfo->unsafeUsage = unsafeUsage ; return fileInfo; } Check::FileInfo * CheckUninitVar::loadFileInfoFromXml(const tinyxml2::XMLElement *xmlElement) const { const std::list &unsafeUsage = CTU::loadUnsafeUsageListFromXml(xmlElement); if (unsafeUsage.empty()) return nullptr; MyFileInfo *fileInfo = new MyFileInfo; fileInfo->unsafeUsage = unsafeUsage; return fileInfo; } bool CheckUninitVar::analyseWholeProgram(const CTU::FileInfo *ctu, const std::list &fileInfo, const Settings& settings, ErrorLogger &errorLogger) { if (!ctu) return false; bool foundErrors = false; (void)settings; // This argument is unused const std::map> callsMap = ctu->getCallsMap(); for (Check::FileInfo *fi1 : fileInfo) { const MyFileInfo *fi = dynamic_cast(fi1); if (!fi) continue; for (const CTU::FileInfo::UnsafeUsage &unsafeUsage : fi->unsafeUsage) { const CTU::FileInfo::FunctionCall *functionCall = nullptr; const std::list &locationList = ctu->getErrorPath(CTU::FileInfo::InvalidValueType::uninit, unsafeUsage, callsMap, "Using argument ARG", &functionCall, false); if (locationList.empty()) continue; const ErrorLogger::ErrorMessage errmsg(locationList, emptyString, Severity::error, "Using argument " + unsafeUsage.myArgumentName + " that points at uninitialized variable " + functionCall->callArgumentExpression, "ctuuninitvar", CWE908, false); errorLogger.reportErr(errmsg); foundErrors = true; } } return foundErrors; }