| //== BoolAssignmentChecker.cpp - Boolean assignment checker -----*- C++ -*--==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This defines BoolAssignmentChecker, a builtin check in ExprEngine that |
| // performs checks for assignment of non-Boolean values to Boolean variables. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" |
| #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" |
| #include "clang/StaticAnalyzer/Core/Checker.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| namespace { |
| class BoolAssignmentChecker : public Checker< check::Bind > { |
| mutable std::unique_ptr<BuiltinBug> BT; |
| void emitReport(ProgramStateRef state, CheckerContext &C) const; |
| public: |
| void checkBind(SVal loc, SVal val, const Stmt *S, CheckerContext &C) const; |
| }; |
| } // end anonymous namespace |
| |
| void BoolAssignmentChecker::emitReport(ProgramStateRef state, |
| CheckerContext &C) const { |
| if (ExplodedNode *N = C.generateNonFatalErrorNode(state)) { |
| if (!BT) |
| BT.reset(new BuiltinBug(this, "Assignment of a non-Boolean value")); |
| |
| C.emitReport( |
| std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N)); |
| } |
| } |
| |
| static bool isBooleanType(QualType Ty) { |
| if (Ty->isBooleanType()) // C++ or C99 |
| return true; |
| |
| if (const TypedefType *TT = Ty->getAs<TypedefType>()) |
| return TT->getDecl()->getName() == "BOOL" || // Objective-C |
| TT->getDecl()->getName() == "_Bool" || // stdbool.h < C99 |
| TT->getDecl()->getName() == "Boolean"; // MacTypes.h |
| |
| return false; |
| } |
| |
| void BoolAssignmentChecker::checkBind(SVal loc, SVal val, const Stmt *S, |
| CheckerContext &C) const { |
| |
| // We are only interested in stores into Booleans. |
| const TypedValueRegion *TR = |
| dyn_cast_or_null<TypedValueRegion>(loc.getAsRegion()); |
| |
| if (!TR) |
| return; |
| |
| QualType valTy = TR->getValueType(); |
| |
| if (!isBooleanType(valTy)) |
| return; |
| |
| // Get the value of the right-hand side. We only care about values |
| // that are defined (UnknownVals and UndefinedVals are handled by other |
| // checkers). |
| Optional<DefinedSVal> DV = val.getAs<DefinedSVal>(); |
| if (!DV) |
| return; |
| |
| // Check if the assigned value meets our criteria for correctness. It must |
| // be a value that is either 0 or 1. One way to check this is to see if |
| // the value is possibly < 0 (for a negative value) or greater than 1. |
| ProgramStateRef state = C.getState(); |
| SValBuilder &svalBuilder = C.getSValBuilder(); |
| ConstraintManager &CM = C.getConstraintManager(); |
| |
| // First, ensure that the value is >= 0. |
| DefinedSVal zeroVal = svalBuilder.makeIntVal(0, valTy); |
| SVal greaterThanOrEqualToZeroVal = |
| svalBuilder.evalBinOp(state, BO_GE, *DV, zeroVal, |
| svalBuilder.getConditionType()); |
| |
| Optional<DefinedSVal> greaterThanEqualToZero = |
| greaterThanOrEqualToZeroVal.getAs<DefinedSVal>(); |
| |
| if (!greaterThanEqualToZero) { |
| // The SValBuilder cannot construct a valid SVal for this condition. |
| // This means we cannot properly reason about it. |
| return; |
| } |
| |
| ProgramStateRef stateLT, stateGE; |
| std::tie(stateGE, stateLT) = CM.assumeDual(state, *greaterThanEqualToZero); |
| |
| // Is it possible for the value to be less than zero? |
| if (stateLT) { |
| // It is possible for the value to be less than zero. We only |
| // want to emit a warning, however, if that value is fully constrained. |
| // If it it possible for the value to be >= 0, then essentially the |
| // value is underconstrained and there is nothing left to be done. |
| if (!stateGE) |
| emitReport(stateLT, C); |
| |
| // In either case, we are done. |
| return; |
| } |
| |
| // If we reach here, it must be the case that the value is constrained |
| // to only be >= 0. |
| assert(stateGE == state); |
| |
| // At this point we know that the value is >= 0. |
| // Now check to ensure that the value is <= 1. |
| DefinedSVal OneVal = svalBuilder.makeIntVal(1, valTy); |
| SVal lessThanEqToOneVal = |
| svalBuilder.evalBinOp(state, BO_LE, *DV, OneVal, |
| svalBuilder.getConditionType()); |
| |
| Optional<DefinedSVal> lessThanEqToOne = |
| lessThanEqToOneVal.getAs<DefinedSVal>(); |
| |
| if (!lessThanEqToOne) { |
| // The SValBuilder cannot construct a valid SVal for this condition. |
| // This means we cannot properly reason about it. |
| return; |
| } |
| |
| ProgramStateRef stateGT, stateLE; |
| std::tie(stateLE, stateGT) = CM.assumeDual(state, *lessThanEqToOne); |
| |
| // Is it possible for the value to be greater than one? |
| if (stateGT) { |
| // It is possible for the value to be greater than one. We only |
| // want to emit a warning, however, if that value is fully constrained. |
| // If it is possible for the value to be <= 1, then essentially the |
| // value is underconstrained and there is nothing left to be done. |
| if (!stateLE) |
| emitReport(stateGT, C); |
| |
| // In either case, we are done. |
| return; |
| } |
| |
| // If we reach here, it must be the case that the value is constrained |
| // to only be <= 1. |
| assert(stateLE == state); |
| } |
| |
| void ento::registerBoolAssignmentChecker(CheckerManager &mgr) { |
| mgr.registerChecker<BoolAssignmentChecker>(); |
| } |
| |
| bool ento::shouldRegisterBoolAssignmentChecker(const LangOptions &LO) { |
| return true; |
| } |