1 //== ObjCAtSyncChecker.cpp - nil mutex checker for @synchronized -*- 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 ObjCAtSyncChecker, a builtin check that checks for null pointers 11 // used as mutexes for @synchronized. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "ClangSACheckers.h" 16 #include "clang/AST/StmtObjC.h" 17 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 18 #include "clang/StaticAnalyzer/Core/Checker.h" 19 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 21 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 22 23 using namespace clang; 24 using namespace ento; 25 26 namespace { 27 class ObjCAtSyncChecker 28 : public Checker< check::PreStmt<ObjCAtSynchronizedStmt> > { 29 mutable std::unique_ptr<BuiltinBug> BT_null; 30 mutable std::unique_ptr<BuiltinBug> BT_undef; 31 32 public: 33 void checkPreStmt(const ObjCAtSynchronizedStmt *S, CheckerContext &C) const; 34 }; 35 } // end anonymous namespace 36 37 void ObjCAtSyncChecker::checkPreStmt(const ObjCAtSynchronizedStmt *S, 38 CheckerContext &C) const { 39 40 const Expr *Ex = S->getSynchExpr(); 41 ProgramStateRef state = C.getState(); 42 SVal V = state->getSVal(Ex, C.getLocationContext()); 43 44 // Uninitialized value used for the mutex? 45 if (V.getAs<UndefinedVal>()) { 46 if (ExplodedNode *N = C.generateErrorNode()) { 47 if (!BT_undef) 48 BT_undef.reset(new BuiltinBug(this, "Uninitialized value used as mutex " 49 "for @synchronized")); 50 auto report = 51 llvm::make_unique<BugReport>(*BT_undef, BT_undef->getDescription(), N); 52 bugreporter::trackNullOrUndefValue(N, Ex, *report); 53 C.emitReport(std::move(report)); 54 } 55 return; 56 } 57 58 if (V.isUnknown()) 59 return; 60 61 // Check for null mutexes. 62 ProgramStateRef notNullState, nullState; 63 std::tie(notNullState, nullState) = state->assume(V.castAs<DefinedSVal>()); 64 65 if (nullState) { 66 if (!notNullState) { 67 // Generate an error node. This isn't a sink since 68 // a null mutex just means no synchronization occurs. 69 if (ExplodedNode *N = C.generateNonFatalErrorNode(nullState)) { 70 if (!BT_null) 71 BT_null.reset(new BuiltinBug( 72 this, "Nil value used as mutex for @synchronized() " 73 "(no synchronization will occur)")); 74 auto report = 75 llvm::make_unique<BugReport>(*BT_null, BT_null->getDescription(), N); 76 bugreporter::trackNullOrUndefValue(N, Ex, *report); 77 78 C.emitReport(std::move(report)); 79 return; 80 } 81 } 82 // Don't add a transition for 'nullState'. If the value is 83 // under-constrained to be null or non-null, assume it is non-null 84 // afterwards. 85 } 86 87 if (notNullState) 88 C.addTransition(notNullState); 89 } 90 91 void ento::registerObjCAtSyncChecker(CheckerManager &mgr) { 92 if (mgr.getLangOpts().ObjC2) 93 mgr.registerChecker<ObjCAtSyncChecker>(); 94 } 95
