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
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
|
//===- ObjCAutoreleaseWriteChecker.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
//
//===----------------------------------------------------------------------===//
//
// This file defines ObjCAutoreleaseWriteChecker which warns against writes
// into autoreleased out parameters which cause crashes.
// An example of a problematic write is a write to @c error in the example
// below:
//
// - (BOOL) mymethod:(NSError *__autoreleasing *)error list:(NSArray*) list {
// [list enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
// NSString *myString = obj;
// if ([myString isEqualToString:@"error"] && error)
// *error = [NSError errorWithDomain:@"MyDomain" code:-1];
// }];
// return false;
// }
//
// Such code will crash on read from `*error` due to the autorelease pool
// in `enumerateObjectsUsingBlock` implementation freeing the error object
// on exit from the function.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "llvm/ADT/Twine.h"
using namespace clang;
using namespace ento;
using namespace ast_matchers;
namespace {
const char *ProblematicWriteBind = "problematicwrite";
const char *CapturedBind = "capturedbind";
const char *ParamBind = "parambind";
const char *IsMethodBind = "ismethodbind";
const char *IsARPBind = "isautoreleasepoolbind";
class ObjCAutoreleaseWriteChecker : public Checker<check::ASTCodeBody> {
public:
void checkASTCodeBody(const Decl *D,
AnalysisManager &AM,
BugReporter &BR) const;
private:
std::vector<std::string> SelectorsWithAutoreleasingPool = {
// Common to NSArray, NSSet, NSOrderedSet
"enumerateObjectsUsingBlock:",
"enumerateObjectsWithOptions:usingBlock:",
// Common to NSArray and NSOrderedSet
"enumerateObjectsAtIndexes:options:usingBlock:",
"indexOfObjectAtIndexes:options:passingTest:",
"indexesOfObjectsAtIndexes:options:passingTest:",
"indexOfObjectPassingTest:",
"indexOfObjectWithOptions:passingTest:",
"indexesOfObjectsPassingTest:",
"indexesOfObjectsWithOptions:passingTest:",
// NSDictionary
"enumerateKeysAndObjectsUsingBlock:",
"enumerateKeysAndObjectsWithOptions:usingBlock:",
"keysOfEntriesPassingTest:",
"keysOfEntriesWithOptions:passingTest:",
// NSSet
"objectsPassingTest:",
"objectsWithOptions:passingTest:",
"enumerateIndexPathsWithOptions:usingBlock:",
// NSIndexSet
"enumerateIndexesWithOptions:usingBlock:",
"enumerateIndexesUsingBlock:",
"enumerateIndexesInRange:options:usingBlock:",
"enumerateRangesUsingBlock:",
"enumerateRangesWithOptions:usingBlock:",
"enumerateRangesInRange:options:usingBlock:",
"indexPassingTest:",
"indexesPassingTest:",
"indexWithOptions:passingTest:",
"indexesWithOptions:passingTest:",
"indexInRange:options:passingTest:",
"indexesInRange:options:passingTest:"
};
std::vector<std::string> FunctionsWithAutoreleasingPool = {
"dispatch_async", "dispatch_group_async", "dispatch_barrier_async"};
};
}
static inline std::vector<llvm::StringRef>
toRefs(const std::vector<std::string> &V) {
return std::vector<llvm::StringRef>(V.begin(), V.end());
}
static decltype(auto)
callsNames(const std::vector<std::string> &FunctionNames) {
return callee(functionDecl(hasAnyName(toRefs(FunctionNames))));
}
static void emitDiagnostics(BoundNodes &Match, const Decl *D, BugReporter &BR,
AnalysisManager &AM,
const ObjCAutoreleaseWriteChecker *Checker) {
AnalysisDeclContext *ADC = AM.getAnalysisDeclContext(D);
const auto *PVD = Match.getNodeAs<ParmVarDecl>(ParamBind);
QualType Ty = PVD->getType();
if (Ty->getPointeeType().getObjCLifetime() != Qualifiers::OCL_Autoreleasing)
return;
const char *ActionMsg = "Write to";
const auto *MarkedStmt = Match.getNodeAs<Expr>(ProblematicWriteBind);
bool IsCapture = false;
// Prefer to warn on write, but if not available, warn on capture.
if (!MarkedStmt) {
MarkedStmt = Match.getNodeAs<Expr>(CapturedBind);
assert(MarkedStmt);
ActionMsg = "Capture of";
IsCapture = true;
}
SourceRange Range = MarkedStmt->getSourceRange();
PathDiagnosticLocation Location = PathDiagnosticLocation::createBegin(
MarkedStmt, BR.getSourceManager(), ADC);
bool IsMethod = Match.getNodeAs<ObjCMethodDecl>(IsMethodBind) != nullptr;
const char *FunctionDescription = IsMethod ? "method" : "function";
bool IsARP = Match.getNodeAs<ObjCAutoreleasePoolStmt>(IsARPBind) != nullptr;
llvm::SmallString<128> BugNameBuf;
llvm::raw_svector_ostream BugName(BugNameBuf);
BugName << ActionMsg
<< " autoreleasing out parameter inside autorelease pool";
llvm::SmallString<128> BugMessageBuf;
llvm::raw_svector_ostream BugMessage(BugMessageBuf);
BugMessage << ActionMsg << " autoreleasing out parameter ";
if (IsCapture)
BugMessage << "'" + PVD->getName() + "' ";
BugMessage << "inside ";
if (IsARP)
BugMessage << "locally-scoped autorelease pool;";
else
BugMessage << "autorelease pool that may exit before "
<< FunctionDescription << " returns;";
BugMessage << " consider writing first to a strong local variable"
" declared outside ";
if (IsARP)
BugMessage << "of the autorelease pool";
else
BugMessage << "of the block";
BR.EmitBasicReport(ADC->getDecl(), Checker, BugName.str(),
categories::MemoryRefCount, BugMessage.str(), Location,
Range);
}
void ObjCAutoreleaseWriteChecker::checkASTCodeBody(const Decl *D,
AnalysisManager &AM,
BugReporter &BR) const {
auto DoublePointerParamM =
parmVarDecl(hasType(hasCanonicalType(pointerType(
pointee(hasCanonicalType(objcObjectPointerType()))))))
.bind(ParamBind);
auto ReferencedParamM =
declRefExpr(to(parmVarDecl(DoublePointerParamM))).bind(CapturedBind);
// Write into a binded object, e.g. *ParamBind = X.
auto WritesIntoM = binaryOperator(
hasLHS(unaryOperator(
hasOperatorName("*"),
hasUnaryOperand(
ignoringParenImpCasts(ReferencedParamM))
)),
hasOperatorName("=")
).bind(ProblematicWriteBind);
auto ArgumentCaptureM = hasAnyArgument(
ignoringParenImpCasts(ReferencedParamM));
auto CapturedInParamM = stmt(anyOf(
callExpr(ArgumentCaptureM),
objcMessageExpr(ArgumentCaptureM)));
// WritesIntoM happens inside a block passed as an argument.
auto WritesOrCapturesInBlockM = hasAnyArgument(allOf(
hasType(hasCanonicalType(blockPointerType())),
forEachDescendant(
stmt(anyOf(WritesIntoM, CapturedInParamM))
)));
auto BlockPassedToMarkedFuncM = stmt(anyOf(
callExpr(allOf(
callsNames(FunctionsWithAutoreleasingPool), WritesOrCapturesInBlockM)),
objcMessageExpr(allOf(
hasAnySelector(toRefs(SelectorsWithAutoreleasingPool)),
WritesOrCapturesInBlockM))
));
// WritesIntoM happens inside an explicit @autoreleasepool.
auto WritesOrCapturesInPoolM =
autoreleasePoolStmt(
forEachDescendant(stmt(anyOf(WritesIntoM, CapturedInParamM))))
.bind(IsARPBind);
auto HasParamAndWritesInMarkedFuncM =
allOf(hasAnyParameter(DoublePointerParamM),
anyOf(forEachDescendant(BlockPassedToMarkedFuncM),
forEachDescendant(WritesOrCapturesInPoolM)));
auto MatcherM = decl(anyOf(
objcMethodDecl(HasParamAndWritesInMarkedFuncM).bind(IsMethodBind),
functionDecl(HasParamAndWritesInMarkedFuncM),
blockDecl(HasParamAndWritesInMarkedFuncM)));
auto Matches = match(MatcherM, *D, AM.getASTContext());
for (BoundNodes Match : Matches)
emitDiagnostics(Match, D, BR, AM, this);
}
void ento::registerAutoreleaseWriteChecker(CheckerManager &Mgr) {
Mgr.registerChecker<ObjCAutoreleaseWriteChecker>();
}
bool ento::shouldRegisterAutoreleaseWriteChecker(const CheckerManager &mgr) {
return true;
}
|
