clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp

   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     mutable std::unique_ptr<BugType> BT;
  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     if (!BT)
  40       BT.reset(new BugType(this, "Assignment of a non-Boolean value"));
  41
  42     StringRef Msg = IsTainted ? "Might assign a tainted non-Boolean value"
  43                               : "Assignment of a non-Boolean value";
  44     C.emitReport(std::make_unique<PathSensitiveBugReport>(*BT, Msg, N));
  45   }
  46 }
  47
  48 static bool isBooleanType(QualType Ty) {
  49   if (Ty->isBooleanType()) // C++ or C99
  50     return true;
  51
  52   if (const TypedefType *TT = Ty->getAs<TypedefType>())
  53     return TT->getDecl()->getName() == "BOOL"   || // Objective-C
  54            TT->getDecl()->getName() == "_Bool"  || // stdbool.h < C99
  55            TT->getDecl()->getName() == "Boolean";  // MacTypes.h
  56
  57   return false;
  58 }
  59
  60 void BoolAssignmentChecker::checkBind(SVal loc, SVal val, const Stmt *S,
  61                                       CheckerContext &C) const {
  62
  63   // We are only interested in stores into Booleans.
  64   const TypedValueRegion *TR =
  65     dyn_cast_or_null<TypedValueRegion>(loc.getAsRegion());
  66
  67   if (!TR)
  68     return;
  69
  70   QualType valTy = TR->getValueType();
  71
  72   if (!isBooleanType(valTy))
  73     return;
  74
  75   // Get the value of the right-hand side.  We only care about values
  76   // that are defined (UnknownVals and UndefinedVals are handled by other
  77   // checkers).
  78   std::optional<NonLoc> NV = val.getAs<NonLoc>();
  79   if (!NV)
  80     return;
  81
  82   // Check if the assigned value meets our criteria for correctness.  It must
  83   // be a value that is either 0 or 1.  One way to check this is to see if
  84   // the value is possibly < 0 (for a negative value) or greater than 1.
  85   ProgramStateRef state = C.getState();
  86   SValBuilder &svalBuilder = C.getSValBuilder();
  87   BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
  88   ConstraintManager &CM = C.getConstraintManager();
  89
  90   llvm::APSInt Zero = BVF.getValue(0, valTy);
  91   llvm::APSInt One = BVF.getValue(1, valTy);
  92
  93   ProgramStateRef StIn, StOut;
  94   std::tie(StIn, StOut) = CM.assumeInclusiveRangeDual(state, *NV, Zero, One);
  95
  96   if (!StIn)
  97     emitReport(StOut, C);
  98   if (StIn && StOut && taint::isTainted(state, *NV))
  99     emitReport(StOut, C, /*IsTainted=*/true);
 100 }
 101
 102 void ento::registerBoolAssignmentChecker(CheckerManager &mgr) {
 103     mgr.registerChecker<BoolAssignmentChecker>();
 104 }
 105
 106 bool ento::shouldRegisterBoolAssignmentChecker(const CheckerManager &mgr) {
 107   return true;
 108 }