1 //===--- UndefinedAssignmentChecker.h ---------------------------*- 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 UndefinedAssignmentChecker, a builtin check in ExprEngine that 11 // checks for assigning undefined values. 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 21 using namespace clang; 22 using namespace ento; 23 24 namespace { 25 class UndefinedAssignmentChecker 26 : public Checker<check::Bind> { 27 mutable std::unique_ptr<BugType> BT; 28 29 public: 30 void checkBind(SVal location, SVal val, const Stmt *S, 31 CheckerContext &C) const; 32 }; 33 } 34 35 void UndefinedAssignmentChecker::checkBind(SVal location, SVal val, 36 const Stmt *StoreE, 37 CheckerContext &C) const { 38 if (!val.isUndef()) 39 return; 40 41 // Do not report assignments of uninitialized values inside swap functions. 42 // This should allow to swap partially uninitialized structs 43 // (radar://14129997) 44 if (const FunctionDecl *EnclosingFunctionDecl = 45 dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl())) 46 if (C.getCalleeName(EnclosingFunctionDecl) == "swap") 47 return; 48 49 ExplodedNode *N = C.generateErrorNode(); 50 51 if (!N) 52 return; 53 54 const char *str = "Assigned value is garbage or undefined"; 55 56 if (!BT) 57 BT.reset(new BuiltinBug(this, str)); 58 59 // Generate a report for this bug. 60 const Expr *ex = nullptr; 61 62 while (StoreE) { 63 if (const UnaryOperator *U = dyn_cast<UnaryOperator>(StoreE)) { 64 str = "The expression is an uninitialized value. " 65 "The computed value will also be garbage"; 66 67 ex = U->getSubExpr(); 68 break; 69 } 70 71 if (const BinaryOperator *B = dyn_cast<BinaryOperator>(StoreE)) { 72 if (B->isCompoundAssignmentOp()) { 73 ProgramStateRef state = C.getState(); 74 if (state->getSVal(B->getLHS(), C.getLocationContext()).isUndef()) { 75 str = "The left expression of the compound assignment is an " 76 "uninitialized value. The computed value will also be garbage"; 77 ex = B->getLHS(); 78 break; 79 } 80 } 81 82 ex = B->getRHS(); 83 break; 84 } 85 86 if (const DeclStmt *DS = dyn_cast<DeclStmt>(StoreE)) { 87 const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl()); 88 ex = VD->getInit(); 89 } 90 91 break; 92 } 93 94 auto R = llvm::make_unique<BugReport>(*BT, str, N); 95 if (ex) { 96 R->addRange(ex->getSourceRange()); 97 bugreporter::trackNullOrUndefValue(N, ex, *R); 98 } 99 C.emitReport(std::move(R)); 100 } 101 102 void ento::registerUndefinedAssignmentChecker(CheckerManager &mgr) { 103 mgr.registerChecker<UndefinedAssignmentChecker>(); 104 } 105