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/BugReporter/BugType.h" 17 #include "clang/StaticAnalyzer/Core/Checker.h" 18 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 21 22 using namespace clang; 23 using namespace ento; 24 25 namespace { 26 class ArrayBoundChecker : 27 public Checker<check::Location> { 28 mutable std::unique_ptr<BuiltinBug> BT; 29 30 public: 31 void checkLocation(SVal l, bool isLoad, const Stmt* S, 32 CheckerContext &C) const; 33 }; 34 } 35 36 void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, const Stmt* LoadS, 37 CheckerContext &C) const { 38 // Check for out of bound array element access. 39 const MemRegion *R = l.getAsRegion(); 40 if (!R) 41 return; 42 43 const ElementRegion *ER = dyn_cast<ElementRegion>(R); 44 if (!ER) 45 return; 46 47 // Get the index of the accessed element. 48 DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>(); 49 50 // Zero index is always in bound, this also passes ElementRegions created for 51 // pointer casts. 52 if (Idx.isZeroConstant()) 53 return; 54 55 ProgramStateRef state = C.getState(); 56 57 // Get the size of the array. 58 DefinedOrUnknownSVal NumElements 59 = C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(), 60 ER->getValueType()); 61 62 ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true); 63 ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false); 64 if (StOutBound && !StInBound) { 65 ExplodedNode *N = C.generateSink(StOutBound); 66 if (!N) 67 return; 68 69 if (!BT) 70 BT.reset(new BuiltinBug( 71 this, "Out-of-bound array access", 72 "Access out-of-bound array element (buffer overflow)")); 73 74 // FIXME: It would be nice to eventually make this diagnostic more clear, 75 // e.g., by referencing the original declaration or by saying *why* this 76 // reference is outside the range. 77 78 // Generate a report for this bug. 79 BugReport *report = 80 new BugReport(*BT, BT->getDescription(), N); 81 82 report->addRange(LoadS->getSourceRange()); 83 C.emitReport(report); 84 return; 85 } 86 87 // Array bound check succeeded. From this point forward the array bound 88 // should always succeed. 89 C.addTransition(StInBound); 90 } 91 92 void ento::registerArrayBoundChecker(CheckerManager &mgr) { 93 mgr.registerChecker<ArrayBoundChecker>(); 94 } 95
