1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25/* $OpenBSD: reallocarray.c,v 1.1 2014/05/08 21:43:49 deraadt Exp $ */
26/*
27 * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
28 *
29 * Permission to use, copy, modify, and distribute this software for any
30 * purpose with or without fee is hereby granted, provided that the above
31 * copyright notice and this permission notice appear in all copies.
32 *
33 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
34 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
35 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
36 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
37 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
38 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
39 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
40 */
41
42#include <sys/types.h>
43#include <errno.h>
44#include <stdint.h>
45#include <stdlib.h>
46
47#ifndef SIZE_MAX
48 #define SIZE_MAX UINTPTR_MAX
49#endif
50
51/*
52 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
53 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
54 */
55#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
56
57void *
58openbsd_reallocarray(void *optr, size_t nmemb, size_t size)
59{
60 if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
61 nmemb > 0 && SIZE_MAX / nmemb < size) {
62 errno = ENOMEM;
63 return NULL;
64 }
65 /*
66 * Head off variations in realloc behavior on different
67 * platforms (reported by MarkR <mrogers6@users.sf.net>)
68 *
69 * The behaviour of reallocarray is implementation-defined if
70 * nmemb or size is zero. It can return NULL or non-NULL
71 * depending on the platform.
72 * https://www.securecoding.cert.org/confluence/display/c/MEM04-C.Beware+of+zero-lengthallocations
73 *
74 * Here are some extracts from realloc man pages on different platforms.
75 *
76 * void realloc( void memblock, size_t size );
77 *
78 * Windows:
79 *
80 * If there is not enough available memory to expand the block
81 * to the given size, the original block is left unchanged,
82 * and NULL is returned. If size is zero, then the block
83 * pointed to by memblock is freed; the return value is NULL,
84 * and memblock is left pointing at a freed block.
85 *
86 * OpenBSD:
87 *
88 * If size or nmemb is equal to 0, a unique pointer to an
89 * access protected, zero sized object is returned. Access via
90 * this pointer will generate a SIGSEGV exception.
91 *
92 * Linux:
93 *
94 * If size was equal to 0, either NULL or a pointer suitable
95 * to be passed to free() is returned.
96 *
97 * OS X:
98 *
99 * If size is zero and ptr is not NULL, a new, minimum sized
100 * object is allocated and the original object is freed.
101 *
102 * It looks like images with zero width or height can trigger
103 * this, and fuzzing behaviour will differ by platform, so
104 * fuzzing on one platform may not detect zero-size allocation
105 * problems on other platforms.
106 */
107 if (size == 0 || nmemb == 0)
108 return NULL;
109 return realloc(optr, size * nmemb);
110}
111