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//=== CXXDeleteChecker.cpp -------------------------------------*- 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 file defines the following new checkers for C++ delete expressions:
//
// * DeleteWithNonVirtualDtorChecker
// Defines a checker for the OOP52-CPP CERT rule: Do not delete a
// polymorphic object without a virtual destructor.
//
// Diagnostic flags -Wnon-virtual-dtor and -Wdelete-non-virtual-dtor
// report if an object with a virtual function but a non-virtual
// destructor exists or is deleted, respectively.
//
// This check exceeds them by comparing the dynamic and static types of
// the object at the point of destruction and only warns if it happens
// through a pointer to a base type without a virtual destructor. The
// check places a note at the last point where the conversion from
// derived to base happened.
//
// * CXXArrayDeleteChecker
// Defines a checker for the EXP51-CPP CERT rule: Do not delete an array
// through a pointer of the incorrect type.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
using namespace clang;
using namespace ento;
namespace {
class CXXDeleteChecker : public Checker<check::PreStmt<CXXDeleteExpr>> {
protected:
class PtrCastVisitor : public BugReporterVisitor {
public:
void Profile(llvm::FoldingSetNodeID &ID) const override {
static int X = 0;
ID.AddPointer(&X);
}
PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
BugReporterContext &BRC,
PathSensitiveBugReport &BR) override;
};
virtual void
checkTypedDeleteExpr(const CXXDeleteExpr *DE, CheckerContext &C,
const TypedValueRegion *BaseClassRegion,
const SymbolicRegion *DerivedClassRegion) const = 0;
public:
void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
};
class DeleteWithNonVirtualDtorChecker : public CXXDeleteChecker {
const BugType BT{
this, "Destruction of a polymorphic object with no virtual destructor"};
void
checkTypedDeleteExpr(const CXXDeleteExpr *DE, CheckerContext &C,
const TypedValueRegion *BaseClassRegion,
const SymbolicRegion *DerivedClassRegion) const override;
};
class CXXArrayDeleteChecker : public CXXDeleteChecker {
const BugType BT{this,
"Deleting an array of polymorphic objects is undefined"};
void
checkTypedDeleteExpr(const CXXDeleteExpr *DE, CheckerContext &C,
const TypedValueRegion *BaseClassRegion,
const SymbolicRegion *DerivedClassRegion) const override;
};
} // namespace
void CXXDeleteChecker::checkPreStmt(const CXXDeleteExpr *DE,
CheckerContext &C) const {
const Expr *DeletedObj = DE->getArgument();
const MemRegion *MR = C.getSVal(DeletedObj).getAsRegion();
if (!MR)
return;
OverloadedOperatorKind DeleteKind =
DE->getOperatorDelete()->getOverloadedOperator();
if (DeleteKind != OO_Delete && DeleteKind != OO_Array_Delete)
return;
const auto *BaseClassRegion = MR->getAs<TypedValueRegion>();
const auto *DerivedClassRegion = MR->getBaseRegion()->getAs<SymbolicRegion>();
if (!BaseClassRegion || !DerivedClassRegion)
return;
checkTypedDeleteExpr(DE, C, BaseClassRegion, DerivedClassRegion);
}
void DeleteWithNonVirtualDtorChecker::checkTypedDeleteExpr(
const CXXDeleteExpr *DE, CheckerContext &C,
const TypedValueRegion *BaseClassRegion,
const SymbolicRegion *DerivedClassRegion) const {
const auto *BaseClass = BaseClassRegion->getValueType()->getAsCXXRecordDecl();
const auto *DerivedClass =
DerivedClassRegion->getSymbol()->getType()->getPointeeCXXRecordDecl();
if (!BaseClass || !DerivedClass)
return;
if (!BaseClass->hasDefinition() || !DerivedClass->hasDefinition())
return;
if (BaseClass->getDestructor()->isVirtual())
return;
if (!DerivedClass->isDerivedFrom(BaseClass))
return;
ExplodedNode *N = C.generateNonFatalErrorNode();
if (!N)
return;
auto R = std::make_unique<PathSensitiveBugReport>(BT, BT.getDescription(), N);
// Mark region of problematic base class for later use in the BugVisitor.
R->markInteresting(BaseClassRegion);
R->addVisitor<PtrCastVisitor>();
C.emitReport(std::move(R));
}
void CXXArrayDeleteChecker::checkTypedDeleteExpr(
const CXXDeleteExpr *DE, CheckerContext &C,
const TypedValueRegion *BaseClassRegion,
const SymbolicRegion *DerivedClassRegion) const {
const auto *BaseClass = BaseClassRegion->getValueType()->getAsCXXRecordDecl();
const auto *DerivedClass =
DerivedClassRegion->getSymbol()->getType()->getPointeeCXXRecordDecl();
if (!BaseClass || !DerivedClass)
return;
if (!BaseClass->hasDefinition() || !DerivedClass->hasDefinition())
return;
if (DE->getOperatorDelete()->getOverloadedOperator() != OO_Array_Delete)
return;
if (!DerivedClass->isDerivedFrom(BaseClass))
return;
ExplodedNode *N = C.generateNonFatalErrorNode();
if (!N)
return;
SmallString<256> Buf;
llvm::raw_svector_ostream OS(Buf);
QualType SourceType = BaseClassRegion->getValueType();
QualType TargetType =
DerivedClassRegion->getSymbol()->getType()->getPointeeType();
OS << "Deleting an array of '" << TargetType.getAsString()
<< "' objects as their base class '"
<< SourceType.getAsString(C.getASTContext().getPrintingPolicy())
<< "' is undefined";
auto R = std::make_unique<PathSensitiveBugReport>(BT, OS.str(), N);
// Mark region of problematic base class for later use in the BugVisitor.
R->markInteresting(BaseClassRegion);
R->addVisitor<PtrCastVisitor>();
C.emitReport(std::move(R));
}
PathDiagnosticPieceRef
CXXDeleteChecker::PtrCastVisitor::VisitNode(const ExplodedNode *N,
BugReporterContext &BRC,
PathSensitiveBugReport &BR) {
const Stmt *S = N->getStmtForDiagnostics();
if (!S)
return nullptr;
const auto *CastE = dyn_cast<CastExpr>(S);
if (!CastE)
return nullptr;
// FIXME: This way of getting base types does not support reference types.
QualType SourceType = CastE->getSubExpr()->getType()->getPointeeType();
QualType TargetType = CastE->getType()->getPointeeType();
if (SourceType.isNull() || TargetType.isNull() || SourceType == TargetType)
return nullptr;
// Region associated with the current cast expression.
const MemRegion *M = N->getSVal(CastE).getAsRegion();
if (!M)
return nullptr;
// Check if target region was marked as problematic previously.
if (!BR.isInteresting(M))
return nullptr;
SmallString<256> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Casting from '" << SourceType.getAsString() << "' to '"
<< TargetType.getAsString() << "' here";
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
N->getLocationContext());
return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(),
/*addPosRange=*/true);
}
void ento::registerCXXArrayDeleteChecker(CheckerManager &mgr) {
mgr.registerChecker<CXXArrayDeleteChecker>();
}
bool ento::shouldRegisterCXXArrayDeleteChecker(const CheckerManager &mgr) {
return true;
}
void ento::registerDeleteWithNonVirtualDtorChecker(CheckerManager &mgr) {
mgr.registerChecker<DeleteWithNonVirtualDtorChecker>();
}
bool ento::shouldRegisterDeleteWithNonVirtualDtorChecker(
const CheckerManager &mgr) {
return true;
}
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