e2617290fc
FORTIFY_SOURCE prevents buffer overflows from occurring. However, the error message often implies that we only detect it, not prevent it. Bring more clarity to the error messages by emphasizing prevention over detection. Change-Id: I5f3e1478673bdfc589e6cc4199fce8e52e197a24
92 lines
3.1 KiB
C++
92 lines
3.1 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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#include <string.h>
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#include <stdlib.h>
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#include "libc_logging.h"
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/*
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* Runtime implementation of __builtin____strncpy_chk.
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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 strncpy check is called if _FORTIFY_SOURCE is defined and
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* greater than 0.
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*/
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extern "C" char* __strncpy_chk(char* __restrict dest, const char* __restrict src,
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size_t len, size_t dest_len)
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{
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if (__predict_false(len > dest_len)) {
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__fortify_chk_fail("strncpy dest buffer overflow prevented",
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BIONIC_EVENT_STRNCPY_BUFFER_OVERFLOW);
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}
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return strncpy(dest, src, len);
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}
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/*
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* __strncpy_chk2
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*
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* This is a variant of __strncpy_chk, but it also checks to make
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* sure we don't read beyond the end of "src". The code for this is
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* based on the original version of strncpy, but modified to check
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* how much we read from "src" at the end of the copy operation.
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*/
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extern "C" char* __strncpy_chk2(char* __restrict dst, const char* __restrict src,
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size_t n, size_t dest_len, size_t src_len)
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{
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if (__predict_false(n > dest_len)) {
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__fortify_chk_fail("strncpy dest buffer overflow prevented",
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BIONIC_EVENT_STRNCPY_BUFFER_OVERFLOW);
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}
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if (n != 0) {
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char* d = dst;
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const char* s = src;
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do {
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if ((*d++ = *s++) == 0) {
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/* NUL pad the remaining n-1 bytes */
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while (--n != 0) {
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*d++ = 0;
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}
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break;
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}
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} while (--n != 0);
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size_t s_copy_len = static_cast<size_t>(s - src);
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if (__predict_false(s_copy_len > src_len)) {
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__fortify_chk_fail("strncpy buffer overrun prevented", 0);
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}
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}
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return dst;
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}
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