forked from OSchip/llvm-project
107 lines
3.4 KiB
C++
107 lines
3.4 KiB
C++
//== DivZeroChecker.cpp - Division by zero 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 DivZeroChecker, a builtin check in ExprEngine that performs
|
|
// checks for division by zeros.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "Taint.h"
|
|
#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;
|
|
using namespace taint;
|
|
|
|
namespace {
|
|
class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
|
|
mutable std::unique_ptr<BuiltinBug> BT;
|
|
void reportBug(const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
|
|
std::unique_ptr<BugReporterVisitor> Visitor = nullptr) const;
|
|
|
|
public:
|
|
void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
static const Expr *getDenomExpr(const ExplodedNode *N) {
|
|
const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
|
|
if (const auto *BE = dyn_cast<BinaryOperator>(S))
|
|
return BE->getRHS();
|
|
return nullptr;
|
|
}
|
|
|
|
void DivZeroChecker::reportBug(
|
|
const char *Msg, ProgramStateRef StateZero, CheckerContext &C,
|
|
std::unique_ptr<BugReporterVisitor> Visitor) const {
|
|
if (ExplodedNode *N = C.generateErrorNode(StateZero)) {
|
|
if (!BT)
|
|
BT.reset(new BuiltinBug(this, "Division by zero"));
|
|
|
|
auto R = std::make_unique<PathSensitiveBugReport>(*BT, Msg, N);
|
|
R->addVisitor(std::move(Visitor));
|
|
bugreporter::trackExpressionValue(N, getDenomExpr(N), *R);
|
|
C.emitReport(std::move(R));
|
|
}
|
|
}
|
|
|
|
void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
|
|
CheckerContext &C) const {
|
|
BinaryOperator::Opcode Op = B->getOpcode();
|
|
if (Op != BO_Div &&
|
|
Op != BO_Rem &&
|
|
Op != BO_DivAssign &&
|
|
Op != BO_RemAssign)
|
|
return;
|
|
|
|
if (!B->getRHS()->getType()->isScalarType())
|
|
return;
|
|
|
|
SVal Denom = C.getSVal(B->getRHS());
|
|
Optional<DefinedSVal> DV = Denom.getAs<DefinedSVal>();
|
|
|
|
// Divide-by-undefined handled in the generic checking for uses of
|
|
// undefined values.
|
|
if (!DV)
|
|
return;
|
|
|
|
// Check for divide by zero.
|
|
ConstraintManager &CM = C.getConstraintManager();
|
|
ProgramStateRef stateNotZero, stateZero;
|
|
std::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV);
|
|
|
|
if (!stateNotZero) {
|
|
assert(stateZero);
|
|
reportBug("Division by zero", stateZero, C);
|
|
return;
|
|
}
|
|
|
|
bool TaintedD = isTainted(C.getState(), *DV);
|
|
if ((stateNotZero && stateZero && TaintedD)) {
|
|
reportBug("Division by a tainted value, possibly zero", stateZero, C,
|
|
std::make_unique<taint::TaintBugVisitor>(*DV));
|
|
return;
|
|
}
|
|
|
|
// If we get here, then the denom should not be zero. We abandon the implicit
|
|
// zero denom case for now.
|
|
C.addTransition(stateNotZero);
|
|
}
|
|
|
|
void ento::registerDivZeroChecker(CheckerManager &mgr) {
|
|
mgr.registerChecker<DivZeroChecker>();
|
|
}
|
|
|
|
bool ento::shouldRegisterDivZeroChecker(const CheckerManager &mgr) {
|
|
return true;
|
|
}
|