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
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
|
//=======- VirtualCallChecker.cpp --------------------------------*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a checker that checks virtual function calls during
// construction or destruction of C++ objects.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace ento;
namespace {
class WalkAST : public StmtVisitor<WalkAST> {
const CheckerBase *Checker;
BugReporter &BR;
AnalysisDeclContext *AC;
/// The root constructor or destructor whose callees are being analyzed.
const CXXMethodDecl *RootMethod = nullptr;
/// Whether the checker should walk into bodies of called functions.
/// Controlled by the "Interprocedural" analyzer-config option.
bool IsInterprocedural = false;
/// Whether the checker should only warn for calls to pure virtual functions
/// (which is undefined behavior) or for all virtual functions (which may
/// may result in unexpected behavior).
bool ReportPureOnly = false;
typedef const CallExpr * WorkListUnit;
typedef SmallVector<WorkListUnit, 20> DFSWorkList;
/// A vector representing the worklist which has a chain of CallExprs.
DFSWorkList WList;
// PreVisited : A CallExpr to this FunctionDecl is in the worklist, but the
// body has not been visited yet.
// PostVisited : A CallExpr to this FunctionDecl is in the worklist, and the
// body has been visited.
enum Kind { NotVisited,
PreVisited, /**< A CallExpr to this FunctionDecl is in the
worklist, but the body has not yet been
visited. */
PostVisited /**< A CallExpr to this FunctionDecl is in the
worklist, and the body has been visited. */
};
/// A DenseMap that records visited states of FunctionDecls.
llvm::DenseMap<const FunctionDecl *, Kind> VisitedFunctions;
/// The CallExpr whose body is currently being visited. This is used for
/// generating bug reports. This is null while visiting the body of a
/// constructor or destructor.
const CallExpr *visitingCallExpr;
public:
WalkAST(const CheckerBase *checker, BugReporter &br, AnalysisDeclContext *ac,
const CXXMethodDecl *rootMethod, bool isInterprocedural,
bool reportPureOnly)
: Checker(checker), BR(br), AC(ac), RootMethod(rootMethod),
IsInterprocedural(isInterprocedural), ReportPureOnly(reportPureOnly),
visitingCallExpr(nullptr) {
// Walking should always start from either a constructor or a destructor.
assert(isa<CXXConstructorDecl>(rootMethod) ||
isa<CXXDestructorDecl>(rootMethod));
}
bool hasWork() const { return !WList.empty(); }
/// This method adds a CallExpr to the worklist and marks the callee as
/// being PreVisited.
void Enqueue(WorkListUnit WLUnit) {
const FunctionDecl *FD = WLUnit->getDirectCallee();
if (!FD || !FD->getBody())
return;
Kind &K = VisitedFunctions[FD];
if (K != NotVisited)
return;
K = PreVisited;
WList.push_back(WLUnit);
}
/// This method returns an item from the worklist without removing it.
WorkListUnit Dequeue() {
assert(!WList.empty());
return WList.back();
}
void Execute() {
while (hasWork()) {
WorkListUnit WLUnit = Dequeue();
const FunctionDecl *FD = WLUnit->getDirectCallee();
assert(FD && FD->getBody());
if (VisitedFunctions[FD] == PreVisited) {
// If the callee is PreVisited, walk its body.
// Visit the body.
SaveAndRestore<const CallExpr *> SaveCall(visitingCallExpr, WLUnit);
Visit(FD->getBody());
// Mark the function as being PostVisited to indicate we have
// scanned the body.
VisitedFunctions[FD] = PostVisited;
continue;
}
// Otherwise, the callee is PostVisited.
// Remove it from the worklist.
assert(VisitedFunctions[FD] == PostVisited);
WList.pop_back();
}
}
// Stmt visitor methods.
void VisitCallExpr(CallExpr *CE);
void VisitCXXMemberCallExpr(CallExpr *CE);
void VisitStmt(Stmt *S) { VisitChildren(S); }
void VisitChildren(Stmt *S);
void ReportVirtualCall(const CallExpr *CE, bool isPure);
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// AST walking.
//===----------------------------------------------------------------------===//
void WalkAST::VisitChildren(Stmt *S) {
for (Stmt *Child : S->children())
if (Child)
Visit(Child);
}
void WalkAST::VisitCallExpr(CallExpr *CE) {
VisitChildren(CE);
if (IsInterprocedural)
Enqueue(CE);
}
void WalkAST::VisitCXXMemberCallExpr(CallExpr *CE) {
VisitChildren(CE);
bool callIsNonVirtual = false;
// Several situations to elide for checking.
if (MemberExpr *CME = dyn_cast<MemberExpr>(CE->getCallee())) {
// If the member access is fully qualified (i.e., X::F), then treat
// this as a non-virtual call and do not warn.
if (CME->getQualifier())
callIsNonVirtual = true;
if (Expr *base = CME->getBase()->IgnoreImpCasts()) {
// Elide analyzing the call entirely if the base pointer is not 'this'.
if (!isa<CXXThisExpr>(base))
return;
// If the most derived class is marked final, we know that now subclass
// can override this member.
if (base->getBestDynamicClassType()->hasAttr<FinalAttr>())
callIsNonVirtual = true;
}
}
// Get the callee.
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(CE->getDirectCallee());
if (MD && MD->isVirtual() && !callIsNonVirtual && !MD->hasAttr<FinalAttr>() &&
!MD->getParent()->hasAttr<FinalAttr>())
ReportVirtualCall(CE, MD->isPure());
if (IsInterprocedural)
Enqueue(CE);
}
void WalkAST::ReportVirtualCall(const CallExpr *CE, bool isPure) {
if (ReportPureOnly && !isPure)
return;
SmallString<100> buf;
llvm::raw_svector_ostream os(buf);
// FIXME: The interprocedural diagnostic experience here is not good.
// Ultimately this checker should be re-written to be path sensitive.
// For now, only diagnose intraprocedurally, by default.
if (IsInterprocedural) {
os << "Call Path : ";
// Name of current visiting CallExpr.
os << *CE->getDirectCallee();
// Name of the CallExpr whose body is current being walked.
if (visitingCallExpr)
os << " <-- " << *visitingCallExpr->getDirectCallee();
// Names of FunctionDecls in worklist with state PostVisited.
for (SmallVectorImpl<const CallExpr *>::iterator I = WList.end(),
E = WList.begin(); I != E; --I) {
const FunctionDecl *FD = (*(I-1))->getDirectCallee();
assert(FD);
if (VisitedFunctions[FD] == PostVisited)
os << " <-- " << *FD;
}
os << "\n";
}
PathDiagnosticLocation CELoc =
PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
SourceRange R = CE->getCallee()->getSourceRange();
os << "Call to ";
if (isPure)
os << "pure ";
os << "virtual function during ";
if (isa<CXXConstructorDecl>(RootMethod))
os << "construction ";
else
os << "destruction ";
if (isPure)
os << "has undefined behavior";
else
os << "will not dispatch to derived class";
BR.EmitBasicReport(AC->getDecl(), Checker,
"Call to virtual function during construction or "
"destruction",
"C++ Object Lifecycle", os.str(), CELoc, R);
}
//===----------------------------------------------------------------------===//
// VirtualCallChecker
//===----------------------------------------------------------------------===//
namespace {
class VirtualCallChecker : public Checker<check::ASTDecl<CXXRecordDecl> > {
public:
DefaultBool isInterprocedural;
DefaultBool isPureOnly;
void checkASTDecl(const CXXRecordDecl *RD, AnalysisManager& mgr,
BugReporter &BR) const {
AnalysisDeclContext *ADC = mgr.getAnalysisDeclContext(RD);
// Check the constructors.
for (const auto *I : RD->ctors()) {
if (!I->isCopyOrMoveConstructor())
if (Stmt *Body = I->getBody()) {
WalkAST walker(this, BR, ADC, I, isInterprocedural, isPureOnly);
walker.Visit(Body);
walker.Execute();
}
}
// Check the destructor.
if (CXXDestructorDecl *DD = RD->getDestructor())
if (Stmt *Body = DD->getBody()) {
WalkAST walker(this, BR, ADC, DD, isInterprocedural, isPureOnly);
walker.Visit(Body);
walker.Execute();
}
}
};
}
void ento::registerVirtualCallChecker(CheckerManager &mgr) {
VirtualCallChecker *checker = mgr.registerChecker<VirtualCallChecker>();
checker->isInterprocedural =
mgr.getAnalyzerOptions().getBooleanOption("Interprocedural", false,
checker);
checker->isPureOnly =
mgr.getAnalyzerOptions().getBooleanOption("PureOnly", false,
checker);
}
|