1 //== ReturnPointerRangeChecker.cpp ------------------------------*- C++ -*--==//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines ReturnPointerRangeChecker, which is a path-sensitive check
10 // which looks for an out-of-bound pointer being returned to callers.
12 //===----------------------------------------------------------------------===//
14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
16 #include "clang/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicSize.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
22 using namespace clang;
26 class ReturnPointerRangeChecker :
27 public Checker< check::PreStmt<ReturnStmt> > {
28 mutable std::unique_ptr<BuiltinBug> BT;
31 void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
35 void ReturnPointerRangeChecker::checkPreStmt(const ReturnStmt *RS,
36 CheckerContext &C) const {
37 ProgramStateRef state = C.getState();
39 const Expr *RetE = RS->getRetValue();
43 SVal V = C.getSVal(RetE);
44 const MemRegion *R = V.getAsRegion();
46 const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
50 DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
51 // Zero index is always in bound, this also passes ElementRegions created for
53 if (Idx.isZeroConstant())
56 // FIXME: All of this out-of-bounds checking should eventually be refactored
57 // into a common place.
58 DefinedOrUnknownSVal ElementCount = getDynamicElementCount(
59 state, ER->getSuperRegion(), C.getSValBuilder(), ER->getValueType());
61 ProgramStateRef StInBound = state->assumeInBound(Idx, ElementCount, true);
62 ProgramStateRef StOutBound = state->assumeInBound(Idx, ElementCount, false);
63 if (StOutBound && !StInBound) {
64 ExplodedNode *N = C.generateErrorNode(StOutBound);
69 // FIXME: This bug correspond to CWE-466. Eventually we should have bug
70 // types explicitly reference such exploit categories (when applicable).
72 BT.reset(new BuiltinBug(
73 this, "Return of pointer value outside of expected range",
74 "Returned pointer value points outside the original object "
75 "(potential buffer overflow)"));
77 // FIXME: It would be nice to eventually make this diagnostic more clear,
78 // e.g., by referencing the original declaration or by saying *why* this
79 // reference is outside the range.
81 // Generate a report for this bug.
83 std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
85 report->addRange(RetE->getSourceRange());
86 C.emitReport(std::move(report));
90 void ento::registerReturnPointerRangeChecker(CheckerManager &mgr) {
91 mgr.registerChecker<ReturnPointerRangeChecker>();
94 bool ento::shouldRegisterReturnPointerRangeChecker(const CheckerManager &mgr) {