1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #undef _FORTIFY_SOURCE
30
31 #include <string.h>
32 #include <stdlib.h>
33 #include "private/libc_logging.h"
34
35 /*
36 * Runtime implementation of __strlen_chk.
37 *
38 * See
39 * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
40 * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
41 * for details.
42 *
43 * This strlen check is called if _FORTIFY_SOURCE is defined and
44 * greater than 0.
45 *
46 * This test is designed to detect code such as:
47 *
48 * int main() {
49 * char buf[10];
50 * memcpy(buf, "1234567890", sizeof(buf));
51 * size_t len = strlen(buf); // segfault here with _FORTIFY_SOURCE
52 * printf("%d\n", len);
53 * return 0;
54 * }
55 *
56 * or anytime strlen reads beyond an object boundary.
57 */
__strlen_chk(const char * s,size_t s_len)58 extern "C" size_t __strlen_chk(const char* s, size_t s_len) {
59 size_t ret = strlen(s);
60
61 if (__predict_false(ret >= s_len)) {
62 __fortify_chk_fail("strlen: prevented read past end of buffer", 0);
63 }
64
65 return ret;
66 }
67