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
22using namespace clang;
23using namespace ento;
24
25namespace {
26class 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
31public:
32 void checkBind(SVal Loc, SVal Val, const Stmt *S, bool AtDeclInit,
33 CheckerContext &C) const;
34};
35} // end anonymous namespace
36
37void BoolAssignmentChecker::emitReport(ProgramStateRef State, CheckerContext &C,
38 bool IsTainted) const {
39 if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
40 StringRef Msg = IsTainted ? "Might assign a tainted non-Boolean value"
41 : "Assignment of a non-Boolean value";
42 C.emitReport(R: std::make_unique<PathSensitiveBugReport>(args: BT, args&: Msg, args&: N));
43 }
44}
45
46static bool isBooleanType(QualType Ty) {
47 if (Ty->isBooleanType()) // C++ or C99
48 return true;
49
50 if (const TypedefType *TT = Ty->getAs<TypedefType>())
51 return TT->getDecl()->getName() == "BOOL" || // Objective-C
52 TT->getDecl()->getName() == "_Bool" || // stdbool.h < C99
53 TT->getDecl()->getName() == "Boolean"; // MacTypes.h
54
55 return false;
56}
57
58void BoolAssignmentChecker::checkBind(SVal Loc, SVal Val, const Stmt *S,
59 bool AtDeclInit,
60 CheckerContext &C) const {
61
62 // We are only interested in stores into Booleans.
63 const TypedValueRegion *TR =
64 dyn_cast_or_null<TypedValueRegion>(Val: Loc.getAsRegion());
65
66 if (!TR)
67 return;
68
69 QualType RegTy = TR->getValueType();
70
71 if (!isBooleanType(Ty: RegTy))
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 std::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 BasicValueFactory &BVF = C.getSValBuilder().getBasicValueFactory();
86 ConstraintManager &CM = C.getConstraintManager();
87
88 llvm::APSInt Zero = BVF.getValue(X: 0, T: RegTy);
89 llvm::APSInt One = BVF.getValue(X: 1, T: RegTy);
90
91 ProgramStateRef StIn, StOut;
92 std::tie(args&: StIn, args&: StOut) = CM.assumeInclusiveRangeDual(State, Value: *NV, From: Zero, To: One);
93
94 if (!StIn)
95 emitReport(State: StOut, C);
96 if (StIn && StOut && taint::isTainted(State, V: *NV))
97 emitReport(State: StOut, C, /*IsTainted=*/true);
98}
99
100void ento::registerBoolAssignmentChecker(CheckerManager &Mgr) {
101 Mgr.registerChecker<BoolAssignmentChecker>();
102}
103
104bool ento::shouldRegisterBoolAssignmentChecker(const CheckerManager &Mgr) {
105 return true;
106}
107