forked from OSchip/llvm-project
126 lines
4.4 KiB
C++
126 lines
4.4 KiB
C++
//=== CastToStructChecker.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 files defines CastToStructChecker, a builtin checker that checks for
|
|
// cast from non-struct pointer to struct pointer and widening struct data cast.
|
|
// This check corresponds to CWE-588.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
|
|
#include "clang/AST/RecursiveASTVisitor.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;
|
|
|
|
namespace {
|
|
class CastToStructVisitor : public RecursiveASTVisitor<CastToStructVisitor> {
|
|
BugReporter &BR;
|
|
const CheckerBase *Checker;
|
|
AnalysisDeclContext *AC;
|
|
|
|
public:
|
|
explicit CastToStructVisitor(BugReporter &B, const CheckerBase *Checker,
|
|
AnalysisDeclContext *A)
|
|
: BR(B), Checker(Checker), AC(A) {}
|
|
bool VisitCastExpr(const CastExpr *CE);
|
|
};
|
|
}
|
|
|
|
bool CastToStructVisitor::VisitCastExpr(const CastExpr *CE) {
|
|
const Expr *E = CE->getSubExpr();
|
|
ASTContext &Ctx = AC->getASTContext();
|
|
QualType OrigTy = Ctx.getCanonicalType(E->getType());
|
|
QualType ToTy = Ctx.getCanonicalType(CE->getType());
|
|
|
|
const PointerType *OrigPTy = dyn_cast<PointerType>(OrigTy.getTypePtr());
|
|
const PointerType *ToPTy = dyn_cast<PointerType>(ToTy.getTypePtr());
|
|
|
|
if (!ToPTy || !OrigPTy)
|
|
return true;
|
|
|
|
QualType OrigPointeeTy = OrigPTy->getPointeeType();
|
|
QualType ToPointeeTy = ToPTy->getPointeeType();
|
|
|
|
if (!ToPointeeTy->isStructureOrClassType())
|
|
return true;
|
|
|
|
// We allow cast from void*.
|
|
if (OrigPointeeTy->isVoidType())
|
|
return true;
|
|
|
|
// Now the cast-to-type is struct pointer, the original type is not void*.
|
|
if (!OrigPointeeTy->isRecordType()) {
|
|
SourceRange Sr[1] = {CE->getSourceRange()};
|
|
PathDiagnosticLocation Loc(CE, BR.getSourceManager(), AC);
|
|
BR.EmitBasicReport(
|
|
AC->getDecl(), Checker, "Cast from non-struct type to struct type",
|
|
categories::LogicError, "Casting a non-structure type to a structure "
|
|
"type and accessing a field can lead to memory "
|
|
"access errors or data corruption.",
|
|
Loc, Sr);
|
|
} else {
|
|
// Don't warn when size of data is unknown.
|
|
const auto *U = dyn_cast<UnaryOperator>(E);
|
|
if (!U || U->getOpcode() != UO_AddrOf)
|
|
return true;
|
|
|
|
// Don't warn for references
|
|
const ValueDecl *VD = nullptr;
|
|
if (const auto *SE = dyn_cast<DeclRefExpr>(U->getSubExpr()))
|
|
VD = SE->getDecl();
|
|
else if (const auto *SE = dyn_cast<MemberExpr>(U->getSubExpr()))
|
|
VD = SE->getMemberDecl();
|
|
if (!VD || VD->getType()->isReferenceType())
|
|
return true;
|
|
|
|
if (ToPointeeTy->isIncompleteType() ||
|
|
OrigPointeeTy->isIncompleteType())
|
|
return true;
|
|
|
|
// Warn when there is widening cast.
|
|
unsigned ToWidth = Ctx.getTypeInfo(ToPointeeTy).Width;
|
|
unsigned OrigWidth = Ctx.getTypeInfo(OrigPointeeTy).Width;
|
|
if (ToWidth <= OrigWidth)
|
|
return true;
|
|
|
|
PathDiagnosticLocation Loc(CE, BR.getSourceManager(), AC);
|
|
BR.EmitBasicReport(AC->getDecl(), Checker, "Widening cast to struct type",
|
|
categories::LogicError,
|
|
"Casting data to a larger structure type and accessing "
|
|
"a field can lead to memory access errors or data "
|
|
"corruption.",
|
|
Loc, CE->getSourceRange());
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
namespace {
|
|
class CastToStructChecker : public Checker<check::ASTCodeBody> {
|
|
public:
|
|
void checkASTCodeBody(const Decl *D, AnalysisManager &Mgr,
|
|
BugReporter &BR) const {
|
|
CastToStructVisitor Visitor(BR, this, Mgr.getAnalysisDeclContext(D));
|
|
Visitor.TraverseDecl(const_cast<Decl *>(D));
|
|
}
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
void ento::registerCastToStructChecker(CheckerManager &mgr) {
|
|
mgr.registerChecker<CastToStructChecker>();
|
|
}
|
|
|
|
bool ento::shouldRegisterCastToStructChecker(const LangOptions &LO) {
|
|
return true;
|
|
}
|