1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
//=- RunLoopAutoreleaseLeakChecker.cpp --------------------------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//
//===----------------------------------------------------------------------===//
//
// A checker for detecting leaks resulting from allocating temporary
// autoreleased objects before starting the main run loop.
//
// Checks for two antipatterns:
// 1. ObjCMessageExpr followed by [[NSRunLoop mainRunLoop] run] in the same
// autorelease pool.
// 2. ObjCMessageExpr followed by [[NSRunLoop mainRunLoop] run] in no
// autorelease pool.
//
// Any temporary objects autoreleased in code called in those expressions
// will not be deallocated until the program exits, and are effectively leaks.
//
//===----------------------------------------------------------------------===//
//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
using namespace clang;
using namespace ento;
using namespace ast_matchers;
namespace {
const char * RunLoopBind = "NSRunLoopM";
const char * RunLoopRunBind = "RunLoopRunM";
const char * OtherMsgBind = "OtherMessageSentM";
const char * AutoreleasePoolBind = "AutoreleasePoolM";
const char * OtherStmtAutoreleasePoolBind = "OtherAutoreleasePoolM";
class RunLoopAutoreleaseLeakChecker : public Checker<check::ASTCodeBody> {
public:
void checkASTCodeBody(const Decl *D,
AnalysisManager &AM,
BugReporter &BR) const;
};
} // end anonymous namespace
/// \return Whether @c A occurs before @c B in traversal of
/// @c Parent.
/// Conceptually a very incomplete/unsound approximation of happens-before
/// relationship (A is likely to be evaluated before B),
/// but useful enough in this case.
static bool seenBefore(const Stmt *Parent, const Stmt *A, const Stmt *B) {
for (const Stmt *C : Parent->children()) {
if (!C) continue;
if (C == A)
return true;
if (C == B)
return false;
return seenBefore(C, A, B);
}
return false;
}
static void emitDiagnostics(BoundNodes &Match,
const Decl *D,
BugReporter &BR,
AnalysisManager &AM,
const RunLoopAutoreleaseLeakChecker *Checker) {
assert(D->hasBody());
const Stmt *DeclBody = D->getBody();
AnalysisDeclContext *ADC = AM.getAnalysisDeclContext(D);
const auto *ME = Match.getNodeAs<ObjCMessageExpr>(OtherMsgBind);
assert(ME);
const auto *AP =
Match.getNodeAs<ObjCAutoreleasePoolStmt>(AutoreleasePoolBind);
const auto *OAP =
Match.getNodeAs<ObjCAutoreleasePoolStmt>(OtherStmtAutoreleasePoolBind);
bool HasAutoreleasePool = (AP != nullptr);
const auto *RL = Match.getNodeAs<ObjCMessageExpr>(RunLoopBind);
const auto *RLR = Match.getNodeAs<Stmt>(RunLoopRunBind);
assert(RLR && "Run loop launch not found");
assert(ME != RLR);
// Launch of run loop occurs before the message-sent expression is seen.
if (seenBefore(DeclBody, RLR, ME))
return;
if (HasAutoreleasePool && (OAP != AP))
return;
PathDiagnosticLocation Location = PathDiagnosticLocation::createBegin(
ME, BR.getSourceManager(), ADC);
SourceRange Range = ME->getSourceRange();
BR.EmitBasicReport(ADC->getDecl(), Checker,
/*Name=*/"Memory leak inside autorelease pool",
/*BugCategory=*/"Memory",
/*Name=*/
(Twine("Temporary objects allocated in the") +
" autorelease pool " +
(HasAutoreleasePool ? "" : "of last resort ") +
"followed by the launch of " +
(RL ? "main run loop " : "xpc_main ") +
"may never get released; consider moving them to a "
"separate autorelease pool")
.str(),
Location, Range);
}
static StatementMatcher getRunLoopRunM(StatementMatcher Extra = anything()) {
StatementMatcher MainRunLoopM =
objcMessageExpr(hasSelector("mainRunLoop"),
hasReceiverType(asString("NSRunLoop")),
Extra)
.bind(RunLoopBind);
StatementMatcher MainRunLoopRunM = objcMessageExpr(hasSelector("run"),
hasReceiver(MainRunLoopM),
Extra).bind(RunLoopRunBind);
StatementMatcher XPCRunM =
callExpr(callee(functionDecl(hasName("xpc_main")))).bind(RunLoopRunBind);
return anyOf(MainRunLoopRunM, XPCRunM);
}
static StatementMatcher getOtherMessageSentM(StatementMatcher Extra = anything()) {
return objcMessageExpr(unless(anyOf(equalsBoundNode(RunLoopBind),
equalsBoundNode(RunLoopRunBind))),
Extra)
.bind(OtherMsgBind);
}
static void
checkTempObjectsInSamePool(const Decl *D, AnalysisManager &AM, BugReporter &BR,
const RunLoopAutoreleaseLeakChecker *Chkr) {
StatementMatcher RunLoopRunM = getRunLoopRunM();
StatementMatcher OtherMessageSentM = getOtherMessageSentM(
hasAncestor(autoreleasePoolStmt().bind(OtherStmtAutoreleasePoolBind)));
StatementMatcher RunLoopInAutorelease =
autoreleasePoolStmt(
hasDescendant(RunLoopRunM),
hasDescendant(OtherMessageSentM)).bind(AutoreleasePoolBind);
DeclarationMatcher GroupM = decl(hasDescendant(RunLoopInAutorelease));
auto Matches = match(GroupM, *D, AM.getASTContext());
for (BoundNodes Match : Matches)
emitDiagnostics(Match, D, BR, AM, Chkr);
}
static void
checkTempObjectsInNoPool(const Decl *D, AnalysisManager &AM, BugReporter &BR,
const RunLoopAutoreleaseLeakChecker *Chkr) {
auto NoPoolM = unless(hasAncestor(autoreleasePoolStmt()));
StatementMatcher RunLoopRunM = getRunLoopRunM(NoPoolM);
StatementMatcher OtherMessageSentM = getOtherMessageSentM(NoPoolM);
DeclarationMatcher GroupM = functionDecl(
isMain(),
hasDescendant(RunLoopRunM),
hasDescendant(OtherMessageSentM)
);
auto Matches = match(GroupM, *D, AM.getASTContext());
for (BoundNodes Match : Matches)
emitDiagnostics(Match, D, BR, AM, Chkr);
}
void RunLoopAutoreleaseLeakChecker::checkASTCodeBody(const Decl *D,
AnalysisManager &AM,
BugReporter &BR) const {
checkTempObjectsInSamePool(D, AM, BR, this);
checkTempObjectsInNoPool(D, AM, BR, this);
}
void ento::registerRunLoopAutoreleaseLeakChecker(CheckerManager &mgr) {
mgr.registerChecker<RunLoopAutoreleaseLeakChecker>();
}
bool ento::shouldRegisterRunLoopAutoreleaseLeakChecker(const CheckerManager &mgr) {
return true;
}
|
