1 //== BoolAssignmentChecker.cpp - Boolean assignment checker -----*- C++ -*--==// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This defines BoolAssignmentChecker, a builtin check in ExprEngine that 10 // performs checks for assignment of non-Boolean values to Boolean variables. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 15 #include "clang/StaticAnalyzer/Checkers/Taint.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 BoolAssignmentChecker : public Checker< check::Bind > { 26 mutable std::unique_ptr<BuiltinBug> BT; 27 void emitReport(ProgramStateRef state, CheckerContext &C, 28 bool IsTainted = false) const; 29 30 public: 31 void checkBind(SVal loc, SVal val, const Stmt *S, CheckerContext &C) const; 32 }; 33 } // end anonymous namespace 34 35 void BoolAssignmentChecker::emitReport(ProgramStateRef state, CheckerContext &C, 36 bool IsTainted) const { 37 if (ExplodedNode *N = C.generateNonFatalErrorNode(state)) { 38 if (!BT) 39 BT.reset(new BuiltinBug(this, "Assignment of a non-Boolean value")); 40 41 StringRef Msg = IsTainted ? "Might assign a tainted non-Boolean value" 42 : "Assignment of a non-Boolean value"; 43 C.emitReport(std::make_unique<PathSensitiveBugReport>(*BT, Msg, N)); 44 } 45 } 46 47 static bool isBooleanType(QualType Ty) { 48 if (Ty->isBooleanType()) // C++ or C99 49 return true; 50 51 if (const TypedefType *TT = Ty->getAs<TypedefType>()) 52 return TT->getDecl()->getName() == "BOOL" || // Objective-C 53 TT->getDecl()->getName() == "_Bool" || // stdbool.h < C99 54 TT->getDecl()->getName() == "Boolean"; // MacTypes.h 55 56 return false; 57 } 58 59 void BoolAssignmentChecker::checkBind(SVal loc, SVal val, const Stmt *S, 60 CheckerContext &C) const { 61 62 // We are only interested in stores into Booleans. 63 const TypedValueRegion *TR = 64 dyn_cast_or_null<TypedValueRegion>(loc.getAsRegion()); 65 66 if (!TR) 67 return; 68 69 QualType valTy = TR->getValueType(); 70 71 if (!isBooleanType(valTy)) 72 return; 73 74 // Get the value of the right-hand side. We only care about values 75 // that are defined (UnknownVals and UndefinedVals are handled by other 76 // checkers). 77 Optional<NonLoc> NV = val.getAs<NonLoc>(); 78 if (!NV) 79 return; 80 81 // Check if the assigned value meets our criteria for correctness. It must 82 // be a value that is either 0 or 1. One way to check this is to see if 83 // the value is possibly < 0 (for a negative value) or greater than 1. 84 ProgramStateRef state = C.getState(); 85 SValBuilder &svalBuilder = C.getSValBuilder(); 86 BasicValueFactory &BVF = svalBuilder.getBasicValueFactory(); 87 ConstraintManager &CM = C.getConstraintManager(); 88 89 llvm::APSInt Zero = BVF.getValue(0, valTy); 90 llvm::APSInt One = BVF.getValue(1, valTy); 91 92 ProgramStateRef StIn, StOut; 93 std::tie(StIn, StOut) = CM.assumeInclusiveRangeDual(state, *NV, Zero, One); 94 95 if (!StIn) 96 emitReport(StOut, C); 97 if (StIn && StOut && taint::isTainted(state, *NV)) 98 emitReport(StOut, C, /*IsTainted=*/true); 99 } 100 101 void ento::registerBoolAssignmentChecker(CheckerManager &mgr) { 102 mgr.registerChecker<BoolAssignmentChecker>(); 103 } 104 105 bool ento::shouldRegisterBoolAssignmentChecker(const CheckerManager &mgr) { 106 return true; 107 } 108