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 #include <optional> 21 22 using namespace clang; 23 using namespace ento; 24 25 namespace { 26 class BoolAssignmentChecker : public Checker< check::Bind > { 27 const BugType BT{this, "Assignment of a non-Boolean value"}; 28 void emitReport(ProgramStateRef state, CheckerContext &C, 29 bool IsTainted = false) const; 30 31 public: 32 void checkBind(SVal loc, SVal val, const Stmt *S, CheckerContext &C) const; 33 }; 34 } // end anonymous namespace 35 36 void BoolAssignmentChecker::emitReport(ProgramStateRef state, CheckerContext &C, 37 bool IsTainted) const { 38 if (ExplodedNode *N = C.generateNonFatalErrorNode(state)) { 39 StringRef Msg = IsTainted ? "Might assign a tainted non-Boolean value" 40 : "Assignment of a non-Boolean value"; 41 C.emitReport(std::make_unique<PathSensitiveBugReport>(BT, Msg, N)); 42 } 43 } 44 45 static bool isBooleanType(QualType Ty) { 46 if (Ty->isBooleanType()) // C++ or C99 47 return true; 48 49 if (const TypedefType *TT = Ty->getAs<TypedefType>()) 50 return TT->getDecl()->getName() == "BOOL" || // Objective-C 51 TT->getDecl()->getName() == "_Bool" || // stdbool.h < C99 52 TT->getDecl()->getName() == "Boolean"; // MacTypes.h 53 54 return false; 55 } 56 57 void BoolAssignmentChecker::checkBind(SVal loc, SVal val, const Stmt *S, 58 CheckerContext &C) const { 59 60 // We are only interested in stores into Booleans. 61 const TypedValueRegion *TR = 62 dyn_cast_or_null<TypedValueRegion>(loc.getAsRegion()); 63 64 if (!TR) 65 return; 66 67 QualType valTy = TR->getValueType(); 68 69 if (!isBooleanType(valTy)) 70 return; 71 72 // Get the value of the right-hand side. We only care about values 73 // that are defined (UnknownVals and UndefinedVals are handled by other 74 // checkers). 75 std::optional<NonLoc> NV = val.getAs<NonLoc>(); 76 if (!NV) 77 return; 78 79 // Check if the assigned value meets our criteria for correctness. It must 80 // be a value that is either 0 or 1. One way to check this is to see if 81 // the value is possibly < 0 (for a negative value) or greater than 1. 82 ProgramStateRef state = C.getState(); 83 SValBuilder &svalBuilder = C.getSValBuilder(); 84 BasicValueFactory &BVF = svalBuilder.getBasicValueFactory(); 85 ConstraintManager &CM = C.getConstraintManager(); 86 87 llvm::APSInt Zero = BVF.getValue(0, valTy); 88 llvm::APSInt One = BVF.getValue(1, valTy); 89 90 ProgramStateRef StIn, StOut; 91 std::tie(StIn, StOut) = CM.assumeInclusiveRangeDual(state, *NV, Zero, One); 92 93 if (!StIn) 94 emitReport(StOut, C); 95 if (StIn && StOut && taint::isTainted(state, *NV)) 96 emitReport(StOut, C, /*IsTainted=*/true); 97 } 98 99 void ento::registerBoolAssignmentChecker(CheckerManager &mgr) { 100 mgr.registerChecker<BoolAssignmentChecker>(); 101 } 102 103 bool ento::shouldRegisterBoolAssignmentChecker(const CheckerManager &mgr) { 104 return true; 105 } 106