ArrayBoundChecker.cpp revision ec8605f1d7ec846dbf51047bfd5c56d32d1ff91c
1//== ArrayBoundChecker.cpp ------------------------------*- 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 file defines ArrayBoundChecker, which is a path-sensitive check 11// which looks for an out-of-bound array element access. 12// 13//===----------------------------------------------------------------------===// 14 15#include "ClangSACheckers.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/BugReporter/BugType.h" 20#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 21 22using namespace clang; 23using namespace ento; 24 25namespace { 26class ArrayBoundChecker : 27 public Checker<check::Location> { 28 mutable llvm::OwningPtr<BuiltinBug> BT; 29public: 30 void checkLocation(SVal l, bool isLoad, CheckerContext &C) const; 31}; 32} 33 34void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, 35 CheckerContext &C) const { 36 // Check for out of bound array element access. 37 const MemRegion *R = l.getAsRegion(); 38 if (!R) 39 return; 40 41 const ElementRegion *ER = dyn_cast<ElementRegion>(R); 42 if (!ER) 43 return; 44 45 // Get the index of the accessed element. 46 DefinedOrUnknownSVal Idx = cast<DefinedOrUnknownSVal>(ER->getIndex()); 47 48 // Zero index is always in bound, this also passes ElementRegions created for 49 // pointer casts. 50 if (Idx.isZeroConstant()) 51 return; 52 53 const GRState *state = C.getState(); 54 55 // Get the size of the array. 56 DefinedOrUnknownSVal NumElements 57 = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(), 58 ER->getValueType()); 59 60 const GRState *StInBound = state->assumeInBound(Idx, NumElements, true); 61 const GRState *StOutBound = state->assumeInBound(Idx, NumElements, false); 62 if (StOutBound && !StInBound) { 63 ExplodedNode *N = C.generateSink(StOutBound); 64 if (!N) 65 return; 66 67 if (!BT) 68 BT.reset(new BuiltinBug("Out-of-bound array access", 69 "Access out-of-bound array element (buffer overflow)")); 70 71 // FIXME: It would be nice to eventually make this diagnostic more clear, 72 // e.g., by referencing the original declaration or by saying *why* this 73 // reference is outside the range. 74 75 // Generate a report for this bug. 76 RangedBugReport *report = 77 new RangedBugReport(*BT, BT->getDescription(), N); 78 79 report->addRange(C.getStmt()->getSourceRange()); 80 C.EmitReport(report); 81 return; 82 } 83 84 // Array bound check succeeded. From this point forward the array bound 85 // should always succeed. 86 assert(StInBound); 87 C.addTransition(StInBound); 88} 89 90void ento::registerArrayBoundChecker(CheckerManager &mgr) { 91 mgr.registerChecker<ArrayBoundChecker>(); 92} 93