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
checkPostCall(const CallEvent & CE,CheckerContext & C) const40 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 if (const CallExpr *CExpr = dyn_cast_or_null<CallExpr>(CE.getOriginExpr());
48 CExpr && !BuildSinks) {
49 if (const Expr *C = CExpr->getCallee())
50 BuildSinks = getFunctionExtInfo(C->getType()).getNoReturn();
51 }
52
53 if (!BuildSinks && CE.isGlobalCFunction()) {
54 if (const IdentifierInfo *II = CE.getCalleeIdentifier()) {
55 // HACK: Some functions are not marked noreturn, and don't return.
56 // Here are a few hardwired ones. If this takes too long, we can
57 // potentially cache these results.
58 BuildSinks
59 = llvm::StringSwitch<bool>(StringRef(II->getName()))
60 .Case("exit", true)
61 .Case("panic", true)
62 .Case("error", true)
63 .Case("Assert", true)
64 // FIXME: This is just a wrapper around throwing an exception.
65 // Eventually inter-procedural analysis should handle this easily.
66 .Case("ziperr", true)
67 .Case("assfail", true)
68 .Case("db_error", true)
69 .Case("__assert", true)
70 .Case("__assert2", true)
71 // For the purpose of static analysis, we do not care that
72 // this MSVC function will return if the user decides to continue.
73 .Case("_wassert", true)
74 .Case("__assert_rtn", true)
75 .Case("__assert_fail", true)
76 .Case("dtrace_assfail", true)
77 .Case("yy_fatal_error", true)
78 .Case("_XCAssertionFailureHandler", true)
79 .Case("_DTAssertionFailureHandler", true)
80 .Case("_TSAssertionFailureHandler", true)
81 .Default(false);
82 }
83 }
84
85 if (BuildSinks)
86 C.generateSink(C.getState(), C.getPredecessor());
87 }
88
checkPostObjCMessage(const ObjCMethodCall & Msg,CheckerContext & C) const89 void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg,
90 CheckerContext &C) const {
91 // Check if the method is annotated with analyzer_noreturn.
92 if (const ObjCMethodDecl *MD = Msg.getDecl()) {
93 MD = MD->getCanonicalDecl();
94 if (MD->hasAttr<AnalyzerNoReturnAttr>()) {
95 C.generateSink(C.getState(), C.getPredecessor());
96 return;
97 }
98 }
99
100 // HACK: This entire check is to handle two messages in the Cocoa frameworks:
101 // -[NSAssertionHandler
102 // handleFailureInMethod:object:file:lineNumber:description:]
103 // -[NSAssertionHandler
104 // handleFailureInFunction:file:lineNumber:description:]
105 // Eventually these should be annotated with __attribute__((noreturn)).
106 // Because ObjC messages use dynamic dispatch, it is not generally safe to
107 // assume certain methods can't return. In cases where it is definitely valid,
108 // see if you can mark the methods noreturn or analyzer_noreturn instead of
109 // adding more explicit checks to this method.
110
111 if (!Msg.isInstanceMessage())
112 return;
113
114 const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();
115 if (!Receiver)
116 return;
117 if (!Receiver->getIdentifier()->isStr("NSAssertionHandler"))
118 return;
119
120 Selector Sel = Msg.getSelector();
121 switch (Sel.getNumArgs()) {
122 default:
123 return;
124 case 4:
125 lazyInitKeywordSelector(HandleFailureInFunctionSel, C.getASTContext(),
126 "handleFailureInFunction", "file", "lineNumber",
127 "description");
128 if (Sel != HandleFailureInFunctionSel)
129 return;
130 break;
131 case 5:
132 lazyInitKeywordSelector(HandleFailureInMethodSel, C.getASTContext(),
133 "handleFailureInMethod", "object", "file",
134 "lineNumber", "description");
135 if (Sel != HandleFailureInMethodSel)
136 return;
137 break;
138 }
139
140 // If we got here, it's one of the messages we care about.
141 C.generateSink(C.getState(), C.getPredecessor());
142 }
143
registerNoReturnFunctionChecker(CheckerManager & mgr)144 void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
145 mgr.registerChecker<NoReturnFunctionChecker>();
146 }
147
shouldRegisterNoReturnFunctionChecker(const CheckerManager & mgr)148 bool ento::shouldRegisterNoReturnFunctionChecker(const CheckerManager &mgr) {
149 return true;
150 }
151