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
|
//===-- BlockInCriticalSectionChecker.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
//
//===----------------------------------------------------------------------===//
//
// Defines a checker for blocks in critical sections. This checker should find
// the calls to blocking functions (for example: sleep, getc, fgets, read,
// recv etc.) inside a critical section. When sleep(x) is called while a mutex
// is held, other threades cannot lock the same mutex. This might take some
// time, leading to bad performance or even deadlock.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace ento;
namespace {
class BlockInCriticalSectionChecker : public Checker<check::PostCall> {
mutable IdentifierInfo *IILockGuard, *IIUniqueLock;
CallDescription LockFn, UnlockFn, SleepFn, GetcFn, FgetsFn, ReadFn, RecvFn,
PthreadLockFn, PthreadTryLockFn, PthreadUnlockFn,
MtxLock, MtxTimedLock, MtxTryLock, MtxUnlock;
StringRef ClassLockGuard, ClassUniqueLock;
mutable bool IdentifierInfoInitialized;
std::unique_ptr<BugType> BlockInCritSectionBugType;
void initIdentifierInfo(ASTContext &Ctx) const;
void reportBlockInCritSection(SymbolRef FileDescSym,
const CallEvent &call,
CheckerContext &C) const;
public:
BlockInCriticalSectionChecker();
bool isBlockingFunction(const CallEvent &Call) const;
bool isLockFunction(const CallEvent &Call) const;
bool isUnlockFunction(const CallEvent &Call) const;
/// Process unlock.
/// Process lock.
/// Process blocking functions (sleep, getc, fgets, read, recv)
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
};
} // end anonymous namespace
REGISTER_TRAIT_WITH_PROGRAMSTATE(MutexCounter, unsigned)
BlockInCriticalSectionChecker::BlockInCriticalSectionChecker()
: IILockGuard(nullptr), IIUniqueLock(nullptr), LockFn({"lock"}),
UnlockFn({"unlock"}), SleepFn({"sleep"}), GetcFn({"getc"}),
FgetsFn({"fgets"}), ReadFn({"read"}), RecvFn({"recv"}),
PthreadLockFn({"pthread_mutex_lock"}),
PthreadTryLockFn({"pthread_mutex_trylock"}),
PthreadUnlockFn({"pthread_mutex_unlock"}), MtxLock({"mtx_lock"}),
MtxTimedLock({"mtx_timedlock"}), MtxTryLock({"mtx_trylock"}),
MtxUnlock({"mtx_unlock"}), ClassLockGuard("lock_guard"),
ClassUniqueLock("unique_lock"), IdentifierInfoInitialized(false) {
// Initialize the bug type.
BlockInCritSectionBugType.reset(
new BugType(this, "Call to blocking function in critical section",
"Blocking Error"));
}
void BlockInCriticalSectionChecker::initIdentifierInfo(ASTContext &Ctx) const {
if (!IdentifierInfoInitialized) {
/* In case of checking C code, or when the corresponding headers are not
* included, we might end up query the identifier table every time when this
* function is called instead of early returning it. To avoid this, a bool
* variable (IdentifierInfoInitialized) is used and the function will be run
* only once. */
IILockGuard = &Ctx.Idents.get(ClassLockGuard);
IIUniqueLock = &Ctx.Idents.get(ClassUniqueLock);
IdentifierInfoInitialized = true;
}
}
bool BlockInCriticalSectionChecker::isBlockingFunction(const CallEvent &Call) const {
return matchesAny(Call, SleepFn, GetcFn, FgetsFn, ReadFn, RecvFn);
}
bool BlockInCriticalSectionChecker::isLockFunction(const CallEvent &Call) const {
if (const auto *Ctor = dyn_cast<CXXConstructorCall>(&Call)) {
auto IdentifierInfo = Ctor->getDecl()->getParent()->getIdentifier();
if (IdentifierInfo == IILockGuard || IdentifierInfo == IIUniqueLock)
return true;
}
return matchesAny(Call, LockFn, PthreadLockFn, PthreadTryLockFn, MtxLock,
MtxTimedLock, MtxTryLock);
}
bool BlockInCriticalSectionChecker::isUnlockFunction(const CallEvent &Call) const {
if (const auto *Dtor = dyn_cast<CXXDestructorCall>(&Call)) {
const auto *DRecordDecl = cast<CXXRecordDecl>(Dtor->getDecl()->getParent());
auto IdentifierInfo = DRecordDecl->getIdentifier();
if (IdentifierInfo == IILockGuard || IdentifierInfo == IIUniqueLock)
return true;
}
return matchesAny(Call, UnlockFn, PthreadUnlockFn, MtxUnlock);
}
void BlockInCriticalSectionChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
initIdentifierInfo(C.getASTContext());
if (!isBlockingFunction(Call)
&& !isLockFunction(Call)
&& !isUnlockFunction(Call))
return;
ProgramStateRef State = C.getState();
unsigned mutexCount = State->get<MutexCounter>();
if (isUnlockFunction(Call) && mutexCount > 0) {
State = State->set<MutexCounter>(--mutexCount);
C.addTransition(State);
} else if (isLockFunction(Call)) {
State = State->set<MutexCounter>(++mutexCount);
C.addTransition(State);
} else if (mutexCount > 0) {
SymbolRef BlockDesc = Call.getReturnValue().getAsSymbol();
reportBlockInCritSection(BlockDesc, Call, C);
}
}
void BlockInCriticalSectionChecker::reportBlockInCritSection(
SymbolRef BlockDescSym, const CallEvent &Call, CheckerContext &C) const {
ExplodedNode *ErrNode = C.generateNonFatalErrorNode();
if (!ErrNode)
return;
std::string msg;
llvm::raw_string_ostream os(msg);
os << "Call to blocking function '" << Call.getCalleeIdentifier()->getName()
<< "' inside of critical section";
auto R = std::make_unique<PathSensitiveBugReport>(*BlockInCritSectionBugType,
os.str(), ErrNode);
R->addRange(Call.getSourceRange());
R->markInteresting(BlockDescSym);
C.emitReport(std::move(R));
}
void ento::registerBlockInCriticalSectionChecker(CheckerManager &mgr) {
mgr.registerChecker<BlockInCriticalSectionChecker>();
}
bool ento::shouldRegisterBlockInCriticalSectionChecker(const CheckerManager &mgr) {
return true;
}
|
