__vsprintf_chk.cpp revision 6861c6f85e6563695c4763e56756398c9d5f6e14 
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#include <stdio.h>
30#include <stdlib.h>
31#include <stdarg.h>
32#include "libc_logging.h"
33
34/*
35 * Runtime implementation of __builtin____vsprintf_chk.
36 *
37 * See
38 *   http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
39 *   http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
40 * for details.
41 *
42 * This vsprintf check is called if _FORTIFY_SOURCE is defined and
43 * greater than 0.
44 */
45extern "C" int __vsprintf_chk(
46        char *dest,
47        int /*flags*/,
48        size_t dest_len_from_compiler,
49        const char *format,
50        va_list va)
51{
52    int ret = vsnprintf(dest, dest_len_from_compiler, format, va);
53
54    if ((size_t) ret >= dest_len_from_compiler) {
55        __fortify_chk_fail("vsprintf prevented write past end of buffer", 0);
56    }
57
58    return ret;
59}
60
61/*
62 * Runtime implementation of __builtin____sprintf_chk.
63 *
64 * See
65 *   http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
66 *   http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
67 * for details.
68 *
69 * This sprintf check is called if _FORTIFY_SOURCE is defined and
70 * greater than 0.
71 */
72extern "C" int __sprintf_chk(
73        char *dest,
74        int flags,
75        size_t dest_len_from_compiler,
76        const char *format, ...)
77{
78    va_list va;
79    int retval;
80
81    va_start(va, format);
82    retval = __vsprintf_chk(dest, flags,
83                             dest_len_from_compiler, format, va);
84    va_end(va);
85
86    return retval;
87}
88