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
|
//=- NSErrorCheckerer.cpp - Coding conventions for uses of NSError -*- 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 CheckNSError, a flow-insenstive check
// that determines if an Objective-C class interface correctly returns
// a non-void return type.
//
// File under feature request PR 2600.
//
//===----------------------------------------------------------------------===//
#include "clang/GR/Checkers/LocalCheckers.h"
#include "clang/GR/BugReporter/BugType.h"
#include "clang/GR/PathSensitive/ExprEngine.h"
#include "clang/GR/Checkers/DereferenceChecker.h"
#include "BasicObjCFoundationChecks.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Decl.h"
#include "llvm/ADT/SmallVector.h"
using namespace clang;
using namespace ento;
namespace {
class NSErrorChecker : public BugType {
const Decl &CodeDecl;
const bool isNSErrorWarning;
IdentifierInfo * const II;
ExprEngine &Eng;
void CheckSignature(const ObjCMethodDecl& MD, QualType& ResultTy,
llvm::SmallVectorImpl<VarDecl*>& ErrorParams);
void CheckSignature(const FunctionDecl& MD, QualType& ResultTy,
llvm::SmallVectorImpl<VarDecl*>& ErrorParams);
bool CheckNSErrorArgument(QualType ArgTy);
bool CheckCFErrorArgument(QualType ArgTy);
void CheckParamDeref(const VarDecl *V, const LocationContext *LC,
const GRState *state, BugReporter& BR);
void EmitRetTyWarning(BugReporter& BR, const Decl& CodeDecl);
public:
NSErrorChecker(const Decl &D, bool isNSError, ExprEngine& eng)
: BugType(isNSError ? "NSError** null dereference"
: "CFErrorRef* null dereference",
"Coding conventions (Apple)"),
CodeDecl(D),
isNSErrorWarning(isNSError),
II(&eng.getContext().Idents.get(isNSErrorWarning ? "NSError":"CFErrorRef")),
Eng(eng) {}
void FlushReports(BugReporter& BR);
};
} // end anonymous namespace
void ento::RegisterNSErrorChecks(BugReporter& BR, ExprEngine &Eng,
const Decl &D) {
BR.Register(new NSErrorChecker(D, true, Eng));
BR.Register(new NSErrorChecker(D, false, Eng));
}
void NSErrorChecker::FlushReports(BugReporter& BR) {
// Get the analysis engine and the exploded analysis graph.
ExplodedGraph& G = Eng.getGraph();
// Get the ASTContext, which is useful for querying type information.
ASTContext &Ctx = BR.getContext();
QualType ResultTy;
llvm::SmallVector<VarDecl*, 5> ErrorParams;
if (const ObjCMethodDecl* MD = dyn_cast<ObjCMethodDecl>(&CodeDecl))
CheckSignature(*MD, ResultTy, ErrorParams);
else if (const FunctionDecl* FD = dyn_cast<FunctionDecl>(&CodeDecl))
CheckSignature(*FD, ResultTy, ErrorParams);
else
return;
if (ErrorParams.empty())
return;
if (ResultTy == Ctx.VoidTy) EmitRetTyWarning(BR, CodeDecl);
for (ExplodedGraph::roots_iterator RI=G.roots_begin(), RE=G.roots_end();
RI!=RE; ++RI) {
// Scan the parameters for an implicit null dereference.
for (llvm::SmallVectorImpl<VarDecl*>::iterator I=ErrorParams.begin(),
E=ErrorParams.end(); I!=E; ++I)
CheckParamDeref(*I, (*RI)->getLocationContext(), (*RI)->getState(), BR);
}
}
void NSErrorChecker::EmitRetTyWarning(BugReporter& BR, const Decl& CodeDecl) {
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
if (isa<ObjCMethodDecl>(CodeDecl))
os << "Method";
else
os << "Function";
os << " accepting ";
os << (isNSErrorWarning ? "NSError**" : "CFErrorRef*");
os << " should have a non-void return value to indicate whether or not an "
"error occurred";
BR.EmitBasicReport(isNSErrorWarning
? "Bad return type when passing NSError**"
: "Bad return type when passing CFError*",
getCategory(), os.str(),
CodeDecl.getLocation());
}
void
NSErrorChecker::CheckSignature(const ObjCMethodDecl& M, QualType& ResultTy,
llvm::SmallVectorImpl<VarDecl*>& ErrorParams) {
ResultTy = M.getResultType();
for (ObjCMethodDecl::param_iterator I=M.param_begin(),
E=M.param_end(); I!=E; ++I) {
QualType T = (*I)->getType();
if (isNSErrorWarning) {
if (CheckNSErrorArgument(T)) ErrorParams.push_back(*I);
}
else if (CheckCFErrorArgument(T))
ErrorParams.push_back(*I);
}
}
void
NSErrorChecker::CheckSignature(const FunctionDecl& F, QualType& ResultTy,
llvm::SmallVectorImpl<VarDecl*>& ErrorParams) {
ResultTy = F.getResultType();
for (FunctionDecl::param_const_iterator I = F.param_begin(),
E = F.param_end(); I != E; ++I) {
QualType T = (*I)->getType();
if (isNSErrorWarning) {
if (CheckNSErrorArgument(T)) ErrorParams.push_back(*I);
}
else if (CheckCFErrorArgument(T))
ErrorParams.push_back(*I);
}
}
bool NSErrorChecker::CheckNSErrorArgument(QualType ArgTy) {
const PointerType* PPT = ArgTy->getAs<PointerType>();
if (!PPT)
return false;
const ObjCObjectPointerType* PT =
PPT->getPointeeType()->getAs<ObjCObjectPointerType>();
if (!PT)
return false;
const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
// FIXME: Can ID ever be NULL?
if (ID)
return II == ID->getIdentifier();
return false;
}
bool NSErrorChecker::CheckCFErrorArgument(QualType ArgTy) {
const PointerType* PPT = ArgTy->getAs<PointerType>();
if (!PPT) return false;
const TypedefType* TT = PPT->getPointeeType()->getAs<TypedefType>();
if (!TT) return false;
return TT->getDecl()->getIdentifier() == II;
}
void NSErrorChecker::CheckParamDeref(const VarDecl *Param,
const LocationContext *LC,
const GRState *rootState,
BugReporter& BR) {
SVal ParamL = rootState->getLValue(Param, LC);
const MemRegion* ParamR = cast<loc::MemRegionVal>(ParamL).getRegionAs<VarRegion>();
assert (ParamR && "Parameters always have VarRegions.");
SVal ParamSVal = rootState->getSVal(ParamR);
// FIXME: For now assume that ParamSVal is symbolic. We need to generalize
// this later.
SymbolRef ParamSym = ParamSVal.getAsLocSymbol();
if (!ParamSym)
return;
// Iterate over the implicit-null dereferences.
ExplodedNode *const* I, *const* E;
llvm::tie(I, E) = GetImplicitNullDereferences(Eng);
for ( ; I != E; ++I) {
const GRState *state = (*I)->getState();
SVal location = state->getSVal((*I)->getLocationAs<StmtPoint>()->getStmt());
if (location.getAsSymbol() != ParamSym)
continue;
// Emit an error.
std::string sbuf;
llvm::raw_string_ostream os(sbuf);
os << "Potential null dereference. According to coding standards ";
if (isNSErrorWarning)
os << "in 'Creating and Returning NSError Objects' the parameter '";
else
os << "documented in CoreFoundation/CFError.h the parameter '";
os << Param << "' may be null.";
BugReport *report = new BugReport(*this, os.str(), *I);
// FIXME: Notable symbols are now part of the report. We should
// add support for notable symbols in BugReport.
// BR.addNotableSymbol(SV->getSymbol());
BR.EmitReport(report);
}
}
|
