Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 1 | //=== PointerSubChecker.cpp - Pointer subtraction checker ------*- C++ -*--===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This files defines PointerSubChecker, a builtin checker that checks for |
| 11 | // pointer subtractions on two pointers pointing to different memory chunks. |
| 12 | // This check corresponds to CWE-469. |
| 13 | // |
| 14 | //===----------------------------------------------------------------------===// |
| 15 | |
| 16 | #include "clang/Analysis/PathSensitive/CheckerVisitor.h" |
| 17 | #include "GRExprEngineInternalChecks.h" |
| 18 | |
| 19 | using namespace clang; |
| 20 | |
| 21 | namespace { |
Kovarththanan Rajaratnam | ba5fb5a | 2009-11-28 06:07:30 +0000 | [diff] [blame] | 22 | class PointerSubChecker |
Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 23 | : public CheckerVisitor<PointerSubChecker> { |
| 24 | BuiltinBug *BT; |
| 25 | public: |
| 26 | PointerSubChecker() : BT(0) {} |
| 27 | static void *getTag(); |
| 28 | void PreVisitBinaryOperator(CheckerContext &C, const BinaryOperator *B); |
| 29 | }; |
| 30 | } |
| 31 | |
| 32 | void *PointerSubChecker::getTag() { |
| 33 | static int x; |
| 34 | return &x; |
| 35 | } |
| 36 | |
| 37 | void PointerSubChecker::PreVisitBinaryOperator(CheckerContext &C, |
| 38 | const BinaryOperator *B) { |
| 39 | // When doing pointer subtraction, if the two pointers do not point to the |
| 40 | // same memory chunk, emit a warning. |
| 41 | if (B->getOpcode() != BinaryOperator::Sub) |
| 42 | return; |
| 43 | |
| 44 | const GRState *state = C.getState(); |
| 45 | SVal LV = state->getSVal(B->getLHS()); |
| 46 | SVal RV = state->getSVal(B->getRHS()); |
| 47 | |
| 48 | const MemRegion *LR = LV.getAsRegion(); |
| 49 | const MemRegion *RR = RV.getAsRegion(); |
| 50 | |
Zhongxing Xu | adca271 | 2009-11-10 02:37:53 +0000 | [diff] [blame] | 51 | if (!(LR && RR)) |
Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 52 | return; |
| 53 | |
Zhongxing Xu | adca271 | 2009-11-10 02:37:53 +0000 | [diff] [blame] | 54 | const MemRegion *BaseLR = LR->getBaseRegion(); |
| 55 | const MemRegion *BaseRR = RR->getBaseRegion(); |
| 56 | |
| 57 | if (BaseLR == BaseRR) |
| 58 | return; |
| 59 | |
| 60 | // Allow arithmetic on different symbolic regions. |
| 61 | if (isa<SymbolicRegion>(BaseLR) || isa<SymbolicRegion>(BaseRR)) |
Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 62 | return; |
| 63 | |
Ted Kremenek | 19d67b5 | 2009-11-23 22:22:01 +0000 | [diff] [blame] | 64 | if (ExplodedNode *N = C.GenerateNode()) { |
Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 65 | if (!BT) |
| 66 | BT = new BuiltinBug("Pointer subtraction", |
Zhongxing Xu | dfed7a1 | 2009-11-09 07:29:39 +0000 | [diff] [blame] | 67 | "Subtraction of two pointers that do not point to " |
| 68 | "the same memory chunk may cause incorrect result."); |
Benjamin Kramer | d02e232 | 2009-11-14 12:08:24 +0000 | [diff] [blame] | 69 | RangedBugReport *R = new RangedBugReport(*BT, BT->getDescription(), N); |
Zhongxing Xu | 3ce2dc3 | 2009-11-09 05:34:10 +0000 | [diff] [blame] | 70 | R->addRange(B->getSourceRange()); |
| 71 | C.EmitReport(R); |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | void clang::RegisterPointerSubChecker(GRExprEngine &Eng) { |
| 76 | Eng.registerCheck(new PointerSubChecker()); |
| 77 | } |