1 //== DivZeroChecker.cpp - Division by zero checker --------------*- C++ -*--==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This defines DivZeroChecker, a builtin check in ExprEngine that performs
11 // checks for division by zeros.
13 //===----------------------------------------------------------------------===//
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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"
21 using namespace clang;
25 class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
26 mutable std::unique_ptr<BuiltinBug> BT;
27 void reportBug(const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
28 std::unique_ptr<BugReporterVisitor> Visitor = nullptr) const;
31 void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
33 } // end anonymous namespace
35 static const Expr *getDenomExpr(const ExplodedNode *N) {
36 const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
37 if (const auto *BE = dyn_cast<BinaryOperator>(S))
42 void DivZeroChecker::reportBug(
43 const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
44 std::unique_ptr<BugReporterVisitor> Visitor) const {
45 if (ExplodedNode *N = C.generateErrorNode(StateZero)) {
47 BT.reset(new BuiltinBug(this, "Division by zero"));
49 auto R = llvm::make_unique<BugReport>(*BT, Msg, N);
50 R->addVisitor(std::move(Visitor));
51 bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
52 C.emitReport(std::move(R));
56 void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
57 CheckerContext &C) const {
58 BinaryOperator::Opcode Op = B->getOpcode();
65 if (!B->getRHS()->getType()->isScalarType())
68 SVal Denom = C.getSVal(B->getRHS());
69 Optional<DefinedSVal> DV = Denom.getAs<DefinedSVal>();
71 // Divide-by-undefined handled in the generic checking for uses of
76 // Check for divide by zero.
77 ConstraintManager &CM = C.getConstraintManager();
78 ProgramStateRef stateNotZero, stateZero;
79 std::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV);
83 reportBug("Division by zero", stateZero, C);
87 bool TaintedD = C.getState()->isTainted(*DV);
88 if ((stateNotZero && stateZero && TaintedD)) {
89 reportBug("Division by a tainted value, possibly zero", stateZero, C,
90 llvm::make_unique<TaintBugVisitor>(*DV));
94 // If we get here, then the denom should not be zero. We abandon the implicit
95 // zero denom case for now.
96 C.addTransition(stateNotZero);
99 void ento::registerDivZeroChecker(CheckerManager &mgr) {
100 mgr.registerChecker<DivZeroChecker>();