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//== ReturnPointerRangeChecker.cpp ------------------------------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines ReturnPointerRangeChecker, which is a path-sensitive check
// which looks for an out-of-bound pointer being returned to callers.
//
//===----------------------------------------------------------------------===//
#include "GRExprEngineInternalChecks.h"
#include "clang/Checker/BugReporter/BugType.h"
#include "clang/Checker/PathSensitive/CheckerVisitor.h"
#include "clang/Checker/PathSensitive/GRExprEngine.h"
using namespace clang;
namespace {
class ReturnPointerRangeChecker :
public CheckerVisitor<ReturnPointerRangeChecker> {
BuiltinBug *BT;
public:
ReturnPointerRangeChecker() : BT(0) {}
static void *getTag();
void PreVisitReturnStmt(CheckerContext &C, const ReturnStmt *RS);
};
}
void clang::RegisterReturnPointerRangeChecker(GRExprEngine &Eng) {
Eng.registerCheck(new ReturnPointerRangeChecker());
}
void *ReturnPointerRangeChecker::getTag() {
static int x = 0; return &x;
}
void ReturnPointerRangeChecker::PreVisitReturnStmt(CheckerContext &C,
const ReturnStmt *RS) {
const GRState *state = C.getState();
const Expr *RetE = RS->getRetValue();
if (!RetE)
return;
SVal V = state->getSVal(RetE);
const MemRegion *R = V.getAsRegion();
if (!R)
return;
R = R->StripCasts();
if (!R)
return;
const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
if (!ER)
return;
DefinedOrUnknownSVal &Idx = cast<DefinedOrUnknownSVal>(ER->getIndex());
// FIXME: All of this out-of-bounds checking should eventually be refactored
// into a common place.
DefinedOrUnknownSVal NumElements
= C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
ER->getValueType(C.getASTContext()));
const GRState *StInBound = state->AssumeInBound(Idx, NumElements, true);
const GRState *StOutBound = state->AssumeInBound(Idx, NumElements, false);
if (StOutBound && !StInBound) {
ExplodedNode *N = C.GenerateSink(StOutBound);
if (!N)
return;
// FIXME: This bug correspond to CWE-466. Eventually we should have bug
// types explicitly reference such exploit categories (when applicable).
if (!BT)
BT = new BuiltinBug("Return of pointer value outside of expected range",
"Returned pointer value points outside the original object "
"(potential buffer overflow)");
// FIXME: It would be nice to eventually make this diagnostic more clear,
// e.g., by referencing the original declaration or by saying *why* this
// reference is outside the range.
// Generate a report for this bug.
RangedBugReport *report =
new RangedBugReport(*BT, BT->getDescription(), N);
report->addRange(RetE->getSourceRange());
C.EmitReport(report);
}
}
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