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//=== CastToStructChecker.cpp - Fixed address usage checker ----*- C++ -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This files defines CastToStructChecker, a builtin checker that checks for
// assignment of a fixed address to a pointer.
// This check corresponds to CWE-588.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/CheckerVisitor.h"
#include "GRExprEngineInternalChecks.h"
using namespace clang;
namespace {
class VISIBILITY_HIDDEN CastToStructChecker
: public CheckerVisitor<CastToStructChecker> {
BuiltinBug *BT;
public:
CastToStructChecker() : BT(0) {}
static void *getTag();
void PreVisitCastExpr(CheckerContext &C, const CastExpr *B);
};
}
void *CastToStructChecker::getTag() {
static int x;
return &x;
}
void CastToStructChecker::PreVisitCastExpr(CheckerContext &C,
const CastExpr *CE) {
const Expr *E = CE->getSubExpr();
ASTContext &Ctx = C.getASTContext();
QualType OrigTy = Ctx.getCanonicalType(E->getType());
QualType ToTy = Ctx.getCanonicalType(CE->getType());
PointerType *OrigPTy = dyn_cast<PointerType>(OrigTy.getTypePtr());
PointerType *ToPTy = dyn_cast<PointerType>(ToTy.getTypePtr());
if (!ToPTy || !OrigPTy)
return;
QualType OrigPointeeTy = OrigPTy->getPointeeType();
QualType ToPointeeTy = ToPTy->getPointeeType();
if (!ToPointeeTy->isStructureType())
return;
// We allow cast from void*.
if (OrigPointeeTy->isVoidType())
return;
// Now the cast-to-type is struct pointer, the original type is not void*.
if (!OrigPointeeTy->isRecordType()) {
if (ExplodedNode *N = C.GenerateNode(CE)) {
if (!BT)
BT = new BuiltinBug("Cast from non-struct type to struct type",
"Casting a non-structure type to a structure type "
"and accessing a field can lead to memory access "
"errors or data corruption.");
RangedBugReport *R = new RangedBugReport(*BT,BT->getDescription(), N);
R->addRange(CE->getSourceRange());
C.EmitReport(R);
}
}
}
void clang::RegisterCastToStructChecker(GRExprEngine &Eng) {
Eng.registerCheck(new CastToStructChecker());
}
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