1 //=== NoReturnFunctionChecker.cpp -------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This defines NoReturnFunctionChecker, which evaluates functions that do not 10 // return to the caller. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 15 #include "clang/AST/Attr.h" 16 #include "clang/Analysis/SelectorExtras.h" 17 #include "clang/StaticAnalyzer/Core/Checker.h" 18 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 21 #include "llvm/ADT/StringSwitch.h" 22 #include <cstdarg> 23 24 using namespace clang; 25 using namespace ento; 26 27 namespace { 28 29 class NoReturnFunctionChecker : public Checker< check::PostCall, 30 check::PostObjCMessage > { 31 mutable Selector HandleFailureInFunctionSel; 32 mutable Selector HandleFailureInMethodSel; 33 public: 34 void checkPostCall(const CallEvent &CE, CheckerContext &C) const; 35 void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const; 36 }; 37 38 } 39 40 void NoReturnFunctionChecker::checkPostCall(const CallEvent &CE, 41 CheckerContext &C) const { 42 bool BuildSinks = false; 43 44 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CE.getDecl())) 45 BuildSinks = FD->hasAttr<AnalyzerNoReturnAttr>() || FD->isNoReturn(); 46 47 const Expr *Callee = CE.getOriginExpr(); 48 if (!BuildSinks && Callee) 49 BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn(); 50 51 if (!BuildSinks && CE.isGlobalCFunction()) { 52 if (const IdentifierInfo *II = CE.getCalleeIdentifier()) { 53 // HACK: Some functions are not marked noreturn, and don't return. 54 // Here are a few hardwired ones. If this takes too long, we can 55 // potentially cache these results. 56 BuildSinks 57 = llvm::StringSwitch<bool>(StringRef(II->getName())) 58 .Case("exit", true) 59 .Case("panic", true) 60 .Case("error", true) 61 .Case("Assert", true) 62 // FIXME: This is just a wrapper around throwing an exception. 63 // Eventually inter-procedural analysis should handle this easily. 64 .Case("ziperr", true) 65 .Case("assfail", true) 66 .Case("db_error", true) 67 .Case("__assert", true) 68 .Case("__assert2", true) 69 // For the purpose of static analysis, we do not care that 70 // this MSVC function will return if the user decides to continue. 71 .Case("_wassert", true) 72 .Case("__assert_rtn", true) 73 .Case("__assert_fail", true) 74 .Case("dtrace_assfail", true) 75 .Case("yy_fatal_error", true) 76 .Case("_XCAssertionFailureHandler", true) 77 .Case("_DTAssertionFailureHandler", true) 78 .Case("_TSAssertionFailureHandler", true) 79 .Default(false); 80 } 81 } 82 83 if (BuildSinks) 84 C.generateSink(C.getState(), C.getPredecessor()); 85 } 86 87 void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg, 88 CheckerContext &C) const { 89 // Check if the method is annotated with analyzer_noreturn. 90 if (const ObjCMethodDecl *MD = Msg.getDecl()) { 91 MD = MD->getCanonicalDecl(); 92 if (MD->hasAttr<AnalyzerNoReturnAttr>()) { 93 C.generateSink(C.getState(), C.getPredecessor()); 94 return; 95 } 96 } 97 98 // HACK: This entire check is to handle two messages in the Cocoa frameworks: 99 // -[NSAssertionHandler 100 // handleFailureInMethod:object:file:lineNumber:description:] 101 // -[NSAssertionHandler 102 // handleFailureInFunction:file:lineNumber:description:] 103 // Eventually these should be annotated with __attribute__((noreturn)). 104 // Because ObjC messages use dynamic dispatch, it is not generally safe to 105 // assume certain methods can't return. In cases where it is definitely valid, 106 // see if you can mark the methods noreturn or analyzer_noreturn instead of 107 // adding more explicit checks to this method. 108 109 if (!Msg.isInstanceMessage()) 110 return; 111 112 const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface(); 113 if (!Receiver) 114 return; 115 if (!Receiver->getIdentifier()->isStr("NSAssertionHandler")) 116 return; 117 118 Selector Sel = Msg.getSelector(); 119 switch (Sel.getNumArgs()) { 120 default: 121 return; 122 case 4: 123 lazyInitKeywordSelector(HandleFailureInFunctionSel, C.getASTContext(), 124 "handleFailureInFunction", "file", "lineNumber", 125 "description"); 126 if (Sel != HandleFailureInFunctionSel) 127 return; 128 break; 129 case 5: 130 lazyInitKeywordSelector(HandleFailureInMethodSel, C.getASTContext(), 131 "handleFailureInMethod", "object", "file", 132 "lineNumber", "description"); 133 if (Sel != HandleFailureInMethodSel) 134 return; 135 break; 136 } 137 138 // If we got here, it's one of the messages we care about. 139 C.generateSink(C.getState(), C.getPredecessor()); 140 } 141 142 void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) { 143 mgr.registerChecker<NoReturnFunctionChecker>(); 144 } 145 146 bool ento::shouldRegisterNoReturnFunctionChecker(const CheckerManager &mgr) { 147 return true; 148 } 149