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comparison gcc/analyzer/sm-malloc.dot @ 145:1830386684a0

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gcc-9.2.0
author anatofuz
date Thu, 13 Feb 2020 11:34:05 +0900
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131:84e7813d76e9 145:1830386684a0
1 /* An overview of the state machine from sm-malloc.cc.
2 Copyright (C) 2019-2020 Free Software Foundation, Inc.
3 Contributed by David Malcolm <dmalcolm@redhat.com>.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21 /* Keep this in-sync with sm-malloc.cc */
22
23 digraph "malloc" {
24
25 /* STATES. */
26
27 /* Start state. */
28 start;
29
30 /* State for a pointer returned from malloc that hasn't been checked for
31 NULL.
32 It could be a pointer to heap-allocated memory, or could be NULL. */
33 unchecked;
34
35 /* State for a pointer that's known to be NULL. */
36 null;
37
38 /* State for a pointer to heap-allocated memory, known to be non-NULL. */
39 nonnull;
40
41 /* State for a pointer to freed memory. */
42 freed;
43
44 /* State for a pointer that's known to not be on the heap (e.g. to a local
45 or global). */
46 non_heap;
47
48 /* Stop state, for pointers we don't want to track any more. */
49 stop;
50
51 /* TRANSITIONS. */
52
53 start -> unchecked [label="on 'X=malloc(...);'"];
54 start -> unchecked [label="on 'X=calloc(...);'"];
55
56 start -> non_heap [label="on 'X=alloca(...);'"];
57 start -> non_heap [label="on 'X=__builtin_alloca(...);'"];
58
59 /* On "free". */
60 start -> freed [label="on 'free(X);'"];
61 unchecked -> freed [label="on 'free(X);'"];
62 nonnull -> freed [label="on 'free(X);'"];
63 freed -> stop [label="on 'free(X);':\n Warn('double-free')"];
64 non_heap -> stop [label="on 'free(X);':\n Warn('free of non-heap')"];
65
66 /* Handle "__attribute__((nonnull))". */
67 unchecked -> nonnull [label="on 'FN(X)' with __attribute__((nonnull)):\nWarn('possible NULL arg')"];
68 null -> stop [label="on 'FN(X)' with __attribute__((nonnull)):\nWarn('NULL arg')"];
69
70 /* is_zero_assignment. */
71 start -> null [label="on 'X = 0;'"];
72 unchecked -> null [label="on 'X = 0;'"];
73 nonnull -> null [label="on 'X = 0;'"];
74 freed -> null [label="on 'X = 0;'"];
75
76 start -> non_heap [label="on 'X = &EXPR;'"];
77
78 /* Handle dereferences. */
79 unchecked -> nonnull [label="on '*X':\nWarn('possible NULL deref')"];
80 null -> stop [label="on '*X':\nWarn('NULL deref')"];
81 freed -> stop [label="on '*X':\nWarn('use after free')"];
82
83 /* on_condition. */
84 unchecked -> nonnull [label="on 'X != 0'"];
85 unchecked -> null [label="on 'X == 0'"];
86
87 unchecked -> stop [label="on leak:\nWarn('leak')"];
88 nonnull -> stop [label="on leak:\nWarn('leak')"];
89 }