MallocSizeofChecker.cpp revision 234353
1276479Sdim// MallocSizeofChecker.cpp - Check for dubious malloc arguments ---*- C++ -*-=// 2249259Sdim// 3249259Sdim// The LLVM Compiler Infrastructure 4249259Sdim// 5249259Sdim// This file is distributed under the University of Illinois Open Source 6249259Sdim// License. See LICENSE.TXT for details. 7249259Sdim// 8249259Sdim//===----------------------------------------------------------------------===// 9249259Sdim// 10276479Sdim// Reports inconsistencies between the casted type of the return value of a 11249259Sdim// malloc/calloc/realloc call and the operand of any sizeof expressions 12249259Sdim// contained within its argument(s). 13249259Sdim// 14280031Sdim//===----------------------------------------------------------------------===// 15280031Sdim 16249259Sdim#include "ClangSACheckers.h" 17249259Sdim#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h" 18249259Sdim#include "clang/StaticAnalyzer/Core/Checker.h" 19249259Sdim#include "clang/StaticAnalyzer/Core/CheckerManager.h" 20249259Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h" 21249259Sdim#include "clang/AST/StmtVisitor.h" 22276479Sdim#include "clang/AST/TypeLoc.h" 23276479Sdim#include "llvm/ADT/SmallString.h" 24276479Sdim 25288943Sdimusing namespace clang; 26249259Sdimusing namespace ento; 27249259Sdim 28276479Sdimnamespace { 29288943Sdim 30249259Sdimtypedef std::pair<const TypeSourceInfo *, const CallExpr *> TypeCallPair; 31276479Sdimtypedef llvm::PointerUnion<const Stmt *, const VarDecl *> ExprParent; 32288943Sdim 33249259Sdimclass CastedAllocFinder 34276479Sdim : public ConstStmtVisitor<CastedAllocFinder, TypeCallPair> { 35249259Sdim IdentifierInfo *II_malloc, *II_calloc, *II_realloc; 36276479Sdim 37288943Sdimpublic: 38288943Sdim struct CallRecord { 39288943Sdim ExprParent CastedExprParent; 40249259Sdim const Expr *CastedExpr; 41276479Sdim const TypeSourceInfo *ExplicitCastType; 42276479Sdim const CallExpr *AllocCall; 43276479Sdim 44276479Sdim CallRecord(ExprParent CastedExprParent, const Expr *CastedExpr, 45276479Sdim const TypeSourceInfo *ExplicitCastType, 46276479Sdim const CallExpr *AllocCall) 47249259Sdim : CastedExprParent(CastedExprParent), CastedExpr(CastedExpr), 48276479Sdim ExplicitCastType(ExplicitCastType), AllocCall(AllocCall) {} 49276479Sdim }; 50276479Sdim 51276479Sdim typedef std::vector<CallRecord> CallVec; 52276479Sdim CallVec Calls; 53276479Sdim 54276479Sdim CastedAllocFinder(ASTContext *Ctx) : 55276479Sdim II_malloc(&Ctx->Idents.get("malloc")), 56276479Sdim II_calloc(&Ctx->Idents.get("calloc")), 57276479Sdim II_realloc(&Ctx->Idents.get("realloc")) {} 58276479Sdim 59276479Sdim void VisitChild(ExprParent Parent, const Stmt *S) { 60288943Sdim TypeCallPair AllocCall = Visit(S); 61288943Sdim if (AllocCall.second && AllocCall.second != S) 62276479Sdim Calls.push_back(CallRecord(Parent, cast<Expr>(S), AllocCall.first, 63276479Sdim AllocCall.second)); 64249259Sdim } 65276479Sdim 66276479Sdim void VisitChildren(const Stmt *S) { 67276479Sdim for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 68276479Sdim I!=E; ++I) 69249259Sdim if (const Stmt *child = *I) 70276479Sdim VisitChild(S, child); 71276479Sdim } 72276479Sdim 73249259Sdim TypeCallPair VisitCastExpr(const CastExpr *E) { 74276479Sdim return Visit(E->getSubExpr()); 75288943Sdim } 76276479Sdim 77276479Sdim TypeCallPair VisitExplicitCastExpr(const ExplicitCastExpr *E) { 78276479Sdim return TypeCallPair(E->getTypeInfoAsWritten(), 79276479Sdim Visit(E->getSubExpr()).second); 80276479Sdim } 81276479Sdim 82276479Sdim TypeCallPair VisitParenExpr(const ParenExpr *E) { 83276479Sdim return Visit(E->getSubExpr()); 84276479Sdim } 85276479Sdim 86249259Sdim TypeCallPair VisitStmt(const Stmt *S) { 87276479Sdim VisitChildren(S); 88276479Sdim return TypeCallPair(); 89276479Sdim } 90249259Sdim 91276479Sdim TypeCallPair VisitCallExpr(const CallExpr *E) { 92276479Sdim VisitChildren(E); 93249259Sdim const FunctionDecl *FD = E->getDirectCallee(); 94276479Sdim if (FD) { 95276479Sdim IdentifierInfo *II = FD->getIdentifier(); 96288943Sdim if (II == II_malloc || II == II_calloc || II == II_realloc) 97288943Sdim return TypeCallPair((const TypeSourceInfo *)0, E); 98288943Sdim } 99249259Sdim return TypeCallPair(); 100249259Sdim } 101249259Sdim 102249259Sdim TypeCallPair VisitDeclStmt(const DeclStmt *S) { 103280031Sdim for (DeclStmt::const_decl_iterator I = S->decl_begin(), E = S->decl_end(); 104 I!=E; ++I) 105 if (const VarDecl *VD = dyn_cast<VarDecl>(*I)) 106 if (const Expr *Init = VD->getInit()) 107 VisitChild(VD, Init); 108 return TypeCallPair(); 109 } 110}; 111 112class SizeofFinder : public ConstStmtVisitor<SizeofFinder> { 113public: 114 std::vector<const UnaryExprOrTypeTraitExpr *> Sizeofs; 115 116 void VisitBinMul(const BinaryOperator *E) { 117 Visit(E->getLHS()); 118 Visit(E->getRHS()); 119 } 120 121 void VisitBinAdd(const BinaryOperator *E) { 122 Visit(E->getLHS()); 123 Visit(E->getRHS()); 124 } 125 126 void VisitImplicitCastExpr(const ImplicitCastExpr *E) { 127 return Visit(E->getSubExpr()); 128 } 129 130 void VisitParenExpr(const ParenExpr *E) { 131 return Visit(E->getSubExpr()); 132 } 133 134 void VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E) { 135 if (E->getKind() != UETT_SizeOf) 136 return; 137 138 Sizeofs.push_back(E); 139 } 140}; 141 142class MallocSizeofChecker : public Checker<check::ASTCodeBody> { 143public: 144 void checkASTCodeBody(const Decl *D, AnalysisManager& mgr, 145 BugReporter &BR) const { 146 AnalysisDeclContext *ADC = mgr.getAnalysisDeclContext(D); 147 CastedAllocFinder Finder(&BR.getContext()); 148 Finder.Visit(D->getBody()); 149 for (CastedAllocFinder::CallVec::iterator i = Finder.Calls.begin(), 150 e = Finder.Calls.end(); i != e; ++i) { 151 QualType CastedType = i->CastedExpr->getType(); 152 if (!CastedType->isPointerType()) 153 continue; 154 QualType PointeeType = CastedType->getAs<PointerType>()->getPointeeType(); 155 if (PointeeType->isVoidType()) 156 continue; 157 158 for (CallExpr::const_arg_iterator ai = i->AllocCall->arg_begin(), 159 ae = i->AllocCall->arg_end(); ai != ae; ++ai) { 160 if (!(*ai)->getType()->isIntegerType()) 161 continue; 162 163 SizeofFinder SFinder; 164 SFinder.Visit(*ai); 165 if (SFinder.Sizeofs.size() != 1) 166 continue; 167 168 QualType SizeofType = SFinder.Sizeofs[0]->getTypeOfArgument(); 169 if (!BR.getContext().hasSameUnqualifiedType(PointeeType, SizeofType)) { 170 const TypeSourceInfo *TSI = 0; 171 if (i->CastedExprParent.is<const VarDecl *>()) { 172 TSI = 173 i->CastedExprParent.get<const VarDecl *>()->getTypeSourceInfo(); 174 } else { 175 TSI = i->ExplicitCastType; 176 } 177 178 SmallString<64> buf; 179 llvm::raw_svector_ostream OS(buf); 180 181 OS << "Result of '" 182 << i->AllocCall->getDirectCallee()->getIdentifier()->getName() 183 << "' is converted to type '" 184 << CastedType.getAsString() << "', whose pointee type '" 185 << PointeeType.getAsString() << "' is incompatible with " 186 << "sizeof operand type '" << SizeofType.getAsString() << "'"; 187 llvm::SmallVector<SourceRange, 4> Ranges; 188 Ranges.push_back(i->AllocCall->getCallee()->getSourceRange()); 189 Ranges.push_back(SFinder.Sizeofs[0]->getSourceRange()); 190 if (TSI) 191 Ranges.push_back(TSI->getTypeLoc().getSourceRange()); 192 193 PathDiagnosticLocation L = 194 PathDiagnosticLocation::createBegin(i->AllocCall->getCallee(), 195 BR.getSourceManager(), ADC); 196 197 BR.EmitBasicReport(D, "allocator sizeof operand mismatch", 198 categories::UnixAPI, 199 OS.str(), 200 L, Ranges.data(), Ranges.size()); 201 } 202 } 203 } 204 } 205}; 206 207} 208 209void ento::registerMallocSizeofChecker(CheckerManager &mgr) { 210 mgr.registerChecker<MallocSizeofChecker>(); 211} 212