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
|
/* Handling for the known behavior of various functions specific to C++.
Copyright (C) 2020-2024 Free Software Foundation, Inc.
Contributed by David Malcolm <dmalcolm@redhat.com>.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#define INCLUDE_MEMORY
#include "system.h"
#include "coretypes.h"
#include "tree.h"
#include "function.h"
#include "basic-block.h"
#include "gimple.h"
#include "analyzer/analyzer.h"
#include "analyzer/analyzer-logging.h"
#include "diagnostic.h"
#include "analyzer/region-model.h"
#include "analyzer/call-details.h"
#include "make-unique.h"
#if ENABLE_ANALYZER
/* Return true if CALL is a non-allocating operator new or operator new []
that contains no user-defined args, i.e. having any signature of:
- void* operator new (std::size_t count, void* ptr);
- void* operator new[] (std::size_t count, void* ptr);
See https://en.cppreference.com/w/cpp/memory/new/operator_new. */
bool is_placement_new_p (const gcall *call)
{
gcc_assert (call);
tree fndecl = gimple_call_fndecl (call);
if (!fndecl || TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
/* Give up on overloaded operator new. */
return false;
if (!is_named_call_p (fndecl, "operator new", call, 2)
&& !is_named_call_p (fndecl, "operator new []", call, 2))
return false;
/* We must distinguish between an allocating non-throwing new
and a non-allocating new.
The former might have one of the following signatures :
void* operator new (std::size_t count, const std::nothrow_t& tag);
void* operator new[] (std::size_t count, const std::nothrow_t& tag);
Whereas a placement new would take a pointer. */
tree arg1_type = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (fndecl)));
return TREE_CODE (TREE_VALUE (arg1_type)) == POINTER_TYPE;
}
namespace ana {
/* Implementations of specific functions. */
/* Handler for "operator new" and "operator new []". */
class kf_operator_new : public known_function
{
public:
bool matches_call_types_p (const call_details &cd) const final override
{
return (cd.num_args () == 1
&& cd.arg_is_size_p (0))
|| (cd.num_args () == 2
&& cd.arg_is_size_p (0)
&& POINTER_TYPE_P (cd.get_arg_type (1)));
}
void impl_call_pre (const call_details &cd) const final override
{
region_model *model = cd.get_model ();
region_model_manager *mgr = cd.get_manager ();
const svalue *size_sval = cd.get_arg_svalue (0);
region_model_context *ctxt = cd.get_ctxt ();
const gcall *call = cd.get_call_stmt ();
/* If the call was actually a placement new, check that accessing
the buffer lhs is placed into does not result in out-of-bounds. */
if (is_placement_new_p (call))
{
const region *ptr_reg = cd.deref_ptr_arg (1);
if (ptr_reg && cd.get_lhs_type ())
{
const svalue *num_bytes_sval = cd.get_arg_svalue (0);
const region *sized_new_reg
= mgr->get_sized_region (ptr_reg,
cd.get_lhs_type (),
num_bytes_sval);
model->check_region_for_write (sized_new_reg,
nullptr,
ctxt);
const svalue *ptr_sval
= mgr->get_ptr_svalue (cd.get_lhs_type (), sized_new_reg);
cd.maybe_set_lhs (ptr_sval);
}
}
/* If the call is an allocating new, then create a heap allocated
region. */
else
{
const region *new_reg
= model->get_or_create_region_for_heap_alloc (size_sval, ctxt);
if (cd.get_lhs_type ())
{
const svalue *ptr_sval
= mgr->get_ptr_svalue (cd.get_lhs_type (), new_reg);
cd.maybe_set_lhs (ptr_sval);
}
}
}
void impl_call_post (const call_details &cd) const final override
{
region_model *model = cd.get_model ();
region_model_manager *mgr = cd.get_manager ();
tree callee_fndecl = cd.get_fndecl_for_call ();
region_model_context *ctxt = cd.get_ctxt ();
/* If the call is guaranteed to return nonnull
then add a nonnull constraint to the allocated region. */
if (!TREE_NOTHROW (callee_fndecl) && flag_exceptions)
{
const svalue *null_sval
= mgr->get_or_create_null_ptr (cd.get_lhs_type ());
const svalue *result
= model->get_store_value (cd.get_lhs_region (), ctxt);
model->add_constraint (result, NE_EXPR, null_sval, ctxt);
}
}
};
/* Handler for "operator delete" and for "operator delete []",
both the sized and unsized variants
(2 arguments and 1 argument respectively). */
class kf_operator_delete : public known_function
{
public:
bool matches_call_types_p (const call_details &cd) const final override
{
return cd.num_args () == 1 or cd.num_args () == 2;
}
void impl_call_post (const call_details &cd) const final override
{
region_model *model = cd.get_model ();
const svalue *ptr_sval = cd.get_arg_svalue (0);
if (const region *freed_reg = ptr_sval->maybe_get_region ())
{
/* If the ptr points to an underlying heap region, delete it,
poisoning pointers. */
model->unbind_region_and_descendents (freed_reg,
POISON_KIND_DELETED);
}
}
};
/* Populate KFM with instances of known functions relating to C++. */
void
register_known_functions_lang_cp (known_function_manager &kfm)
{
kfm.add ("operator new", make_unique<kf_operator_new> ());
kfm.add ("operator new []", make_unique<kf_operator_new> ());
kfm.add ("operator delete", make_unique<kf_operator_delete> ());
kfm.add ("operator delete []", make_unique<kf_operator_delete> ());
}
} // namespace ana
#endif /* #if ENABLE_ANALYZER */
|