f3913b5b68
Two changes:
1) Detect memory read overruns.
For example:
int main() {
char buf[10];
memcpy(buf, "abcde", sizeof(buf));
sprintf("%s\n", buf);
}
because "abcde" is only 6 bytes, copying 10 bytes from it is a bug.
This particular bug will be detected at compile time. Other similar
bugs may be detected at runtime.
2) Detect overlapping buffers on memcpy()
It is a bug to call memcpy() on buffers which overlap. For
example, the following code is buggy:
char buf3[0x800];
char *first_half = &buf3[0x400];
char *second_half = &buf3[1];
memset(buf3, 0, sizeof(buf3));
memcpy(first_half, second_half, 0x400);
printf("1: %s\n", buf3);
We now detect this at compile and run time.
Change-Id: I092bd89f11f18e08e8a9dda0ca903aaea8e06d91
73 lines
2.7 KiB
C
73 lines
2.7 KiB
C
/*
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* Copyright (C) 2012 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#undef _FORTIFY_SOURCE
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#include <string.h>
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#include <stdlib.h>
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#include <private/logd.h>
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/*
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* Runtime implementation of __memcpy_chk2.
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*
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* See
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* http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
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* http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
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* for details.
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*
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* This memcpy check is called if _FORTIFY_SOURCE is defined and
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* greater than 0.
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*/
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void *__memcpy_chk2(void *dest, const void *src,
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size_t copy_amount, size_t dest_len, size_t src_len)
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{
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char *d = (char *) dest;
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const char *s = (const char *) src;
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if (__builtin_expect(copy_amount > dest_len, 0)) {
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__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
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"*** memcpy buffer overflow detected ***\n");
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__libc_android_log_event_uid(BIONIC_EVENT_MEMCPY_BUFFER_OVERFLOW);
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abort();
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}
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if (__builtin_expect(copy_amount > src_len, 0)) {
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__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
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"*** memcpy read overflow detected ***\n");
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abort();
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}
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if (__builtin_expect(((d <= s) && ((size_t)(s - d) < copy_amount))
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|| ((d >= s) && ((size_t)(d - s) < copy_amount)), 0)) {
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__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
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"*** memcpy memory overlap detected ***\n");
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abort();
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}
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return memcpy(dest, src, copy_amount);
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}
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