freebsd-dev/lib/libc/stdlib/reallocf.c
Jaakko Heinonen 967e82cae0 In reallocf(3), free the memory only when size != 0. Otherwise, when the
System V compatibility option (malloc "V" flag) is in effect a zero sized
reallocf() could cause a double free.

PR:		bin/141753
Submitted by:	Dan Lukes
2010-03-03 15:43:26 +00:00

49 lines
1.8 KiB
C

/*-
* Copyright (c) 1998, M. Warner Losh <imp@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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 AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stdlib.h>
void *
reallocf(void *ptr, size_t size)
{
void *nptr;
nptr = realloc(ptr, size);
/*
* When the System V compatibility option (malloc "V" flag) is
* in effect, realloc(ptr, 0) frees the memory and returns NULL.
* So, to avoid double free, call free() only when size != 0.
* realloc(ptr, 0) can't fail when ptr != NULL.
*/
if (!nptr && ptr && size != 0)
free(ptr);
return (nptr);
}