1 //=== UndefResultChecker.cpp ------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This defines UndefResultChecker, a builtin check in ExprEngine that 11 // performs checks for undefined results of non-assignment binary operators. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "ClangSACheckers.h" 16 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 17 #include "clang/StaticAnalyzer/Core/Checker.h" 18 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 21 #include "llvm/ADT/SmallString.h" 22 #include "llvm/Support/raw_ostream.h" 23 24 using namespace clang; 25 using namespace ento; 26 27 namespace { 28 class UndefResultChecker 29 : public Checker< check::PostStmt<BinaryOperator> > { 30 31 mutable std::unique_ptr<BugType> BT; 32 33 public: 34 void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const; 35 }; 36 } // end anonymous namespace 37 38 void UndefResultChecker::checkPostStmt(const BinaryOperator *B, 39 CheckerContext &C) const { 40 ProgramStateRef state = C.getState(); 41 const LocationContext *LCtx = C.getLocationContext(); 42 if (state->getSVal(B, LCtx).isUndef()) { 43 44 // Do not report assignments of uninitialized values inside swap functions. 45 // This should allow to swap partially uninitialized structs 46 // (radar://14129997) 47 if (const FunctionDecl *EnclosingFunctionDecl = 48 dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl())) 49 if (C.getCalleeName(EnclosingFunctionDecl) == "swap") 50 return; 51 52 // Generate an error node. 53 ExplodedNode *N = C.generateErrorNode(); 54 if (!N) 55 return; 56 57 if (!BT) 58 BT.reset( 59 new BuiltinBug(this, "Result of operation is garbage or undefined")); 60 61 SmallString<256> sbuf; 62 llvm::raw_svector_ostream OS(sbuf); 63 const Expr *Ex = nullptr; 64 bool isLeft = true; 65 66 if (state->getSVal(B->getLHS(), LCtx).isUndef()) { 67 Ex = B->getLHS()->IgnoreParenCasts(); 68 isLeft = true; 69 } 70 else if (state->getSVal(B->getRHS(), LCtx).isUndef()) { 71 Ex = B->getRHS()->IgnoreParenCasts(); 72 isLeft = false; 73 } 74 75 if (Ex) { 76 OS << "The " << (isLeft ? "left" : "right") 77 << " operand of '" 78 << BinaryOperator::getOpcodeStr(B->getOpcode()) 79 << "' is a garbage value"; 80 } 81 else { 82 // Neither operand was undefined, but the result is undefined. 83 OS << "The result of the '" 84 << BinaryOperator::getOpcodeStr(B->getOpcode()) 85 << "' expression is undefined"; 86 } 87 auto report = llvm::make_unique<BugReport>(*BT, OS.str(), N); 88 if (Ex) { 89 report->addRange(Ex->getSourceRange()); 90 bugreporter::trackNullOrUndefValue(N, Ex, *report); 91 } 92 else 93 bugreporter::trackNullOrUndefValue(N, B, *report); 94 95 C.emitReport(std::move(report)); 96 } 97 } 98 99 void ento::registerUndefResultChecker(CheckerManager &mgr) { 100 mgr.registerChecker<UndefResultChecker>(); 101 } 102
