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lib/libc/secure/__fwrite_chk.c
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/*- | |||||
* Copyright (C) 2015 The Android Open Source Project | |||||
* All rights reserved. | |||||
* | |||||
* Redistribution and use in source and binary forms, with or without | |||||
* modification, are permitted provided that the following conditions | |||||
* are met: | |||||
* * Redistributions of source code must retain the above copyright | |||||
* notice, this list of conditions and the following disclaimer. | |||||
* * Redistributions in binary form must reproduce the above copyright | |||||
* notice, this list of conditions and the following disclaimer in | |||||
* the documentation and/or other materials provided with the | |||||
* distribution. | |||||
* | |||||
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |||||
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |||||
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |||||
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |||||
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |||||
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |||||
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS | |||||
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED | |||||
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | |||||
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |||||
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |||||
* SUCH DAMAGE. | |||||
* | |||||
* bionic rev: fed2659869ec41a93f655be8058568ddab419e01 | |||||
* | |||||
* $FreeBSD$ | |||||
*/ | |||||
#undef _FORTIFY_SOURCE | |||||
#include <sys/cdefs.h> | |||||
#include <secure/security.h> | |||||
#include <stdio.h> | |||||
#include "secure/_stdio.h" | |||||
size_t | |||||
__fwrite_chk(const void * __restrict ptr, size_t size, size_t nmemb, FILE * __restrict stream, size_t bos) | |||||
{ | |||||
size_t total; | |||||
if (__predict_false(bos == __FORTIFY_UNKNOWN_SIZE)) | |||||
theraven: Logic error. If we don't statically know the object size, then we skip the overflow checking. | |||||
return (fwrite(ptr, size, nmemb, stream)); | |||||
Not Done Inline ActionsAll of these __predict_false() cases are going to make code slower if compiled with the system compiler (which, unconditionally, is setting this to __FORTIFY_UNKNOWN_SIZE). theraven: All of these `__predict_false()` cases are going to make code slower if compiled with the… | |||||
if (__predict_false(__size_mul_overflow(size, nmemb, &total))) { | |||||
// overflow: trigger the error path in fwrite | |||||
return (fwrite(ptr, size, nmemb, stream)); | |||||
} | |||||
if (__predict_false(total > bos)) | |||||
__fortify_chk_fail("fwrite: prevented read past end of buffer"); | |||||
return (fwrite(ptr, size, nmemb, stream)); | |||||
} |
Logic error. If we don't statically know the object size, then we skip the overflow checking. If there is an overflow, then we don't emit an error, we do exactly the same thing as if we'd not done the overflow checking.