1 //== DivZeroChecker.cpp - Division by zero 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 defines DivZeroChecker, a builtin check in ExprEngine that performs 11 // checks for division by zeros. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "ClangSACheckers.h" 16 #include "clang/StaticAnalyzer/Core/CheckerV2.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 21 using namespace clang; 22 using namespace ento; 23 24 namespace { 25 class DivZeroChecker : public CheckerV2< check::PreStmt<BinaryOperator> > { 26 mutable llvm::OwningPtr<BuiltinBug> BT; 27 public: 28 void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const; 29 }; 30 } // end anonymous namespace 31 32 void DivZeroChecker::checkPreStmt(const BinaryOperator *B, 33 CheckerContext &C) const { 34 BinaryOperator::Opcode Op = B->getOpcode(); 35 if (Op != BO_Div && 36 Op != BO_Rem && 37 Op != BO_DivAssign && 38 Op != BO_RemAssign) 39 return; 40 41 if (!B->getRHS()->getType()->isIntegerType() || 42 !B->getRHS()->getType()->isScalarType()) 43 return; 44 45 SVal Denom = C.getState()->getSVal(B->getRHS()); 46 const DefinedSVal *DV = dyn_cast<DefinedSVal>(&Denom); 47 48 // Divide-by-undefined handled in the generic checking for uses of 49 // undefined values. 50 if (!DV) 51 return; 52 53 // Check for divide by zero. 54 ConstraintManager &CM = C.getConstraintManager(); 55 const GRState *stateNotZero, *stateZero; 56 llvm::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV); 57 58 if (stateZero && !stateNotZero) { 59 if (ExplodedNode *N = C.generateSink(stateZero)) { 60 if (!BT) 61 BT.reset(new BuiltinBug("Division by zero")); 62 63 EnhancedBugReport *R = 64 new EnhancedBugReport(*BT, BT->getDescription(), N); 65 66 R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, 67 bugreporter::GetDenomExpr(N)); 68 69 C.EmitReport(R); 70 } 71 return; 72 } 73 74 // If we get here, then the denom should not be zero. We abandon the implicit 75 // zero denom case for now. 76 C.addTransition(stateNotZero); 77 } 78 79 void ento::registerDivZeroChecker(CheckerManager &mgr) { 80 mgr.registerChecker<DivZeroChecker>(); 81 } 82