75 lines
2.2 KiB
C
75 lines
2.2 KiB
C
/*
|
|
* Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
|
|
* SPDX-License-Identifier: MIT
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
#include <errno.h>
|
|
#include <stdint.h>
|
|
#include <stdlib.h>
|
|
|
|
#ifndef SIZE_MAX
|
|
#define SIZE_MAX UINTPTR_MAX
|
|
#endif
|
|
|
|
/*
|
|
* This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
|
|
* if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
|
|
*/
|
|
#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
|
|
|
|
void *
|
|
openbsd_reallocarray(void *optr, size_t nmemb, size_t size)
|
|
{
|
|
if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
|
|
nmemb > 0 && SIZE_MAX / nmemb < size) {
|
|
errno = ENOMEM;
|
|
return NULL;
|
|
}
|
|
/*
|
|
* Head off variations in realloc behavior on different
|
|
* platforms (reported by MarkR <mrogers6@users.sf.net>)
|
|
*
|
|
* The behaviour of reallocarray is implementation-defined if
|
|
* nmemb or size is zero. It can return NULL or non-NULL
|
|
* depending on the platform.
|
|
* https://www.securecoding.cert.org/confluence/display/c/MEM04-C.Beware+of+zero-lengthallocations
|
|
*
|
|
* Here are some extracts from realloc man pages on different platforms.
|
|
*
|
|
* void realloc( void memblock, size_t size );
|
|
*
|
|
* Windows:
|
|
*
|
|
* If there is not enough available memory to expand the block
|
|
* to the given size, the original block is left unchanged,
|
|
* and NULL is returned. If size is zero, then the block
|
|
* pointed to by memblock is freed; the return value is NULL,
|
|
* and memblock is left pointing at a freed block.
|
|
*
|
|
* OpenBSD:
|
|
*
|
|
* If size or nmemb is equal to 0, a unique pointer to an
|
|
* access protected, zero sized object is returned. Access via
|
|
* this pointer will generate a SIGSEGV exception.
|
|
*
|
|
* Linux:
|
|
*
|
|
* If size was equal to 0, either NULL or a pointer suitable
|
|
* to be passed to free() is returned.
|
|
*
|
|
* OS X:
|
|
*
|
|
* If size is zero and ptr is not NULL, a new, minimum sized
|
|
* object is allocated and the original object is freed.
|
|
*
|
|
* It looks like images with zero width or height can trigger
|
|
* this, and fuzzing behaviour will differ by platform, so
|
|
* fuzzing on one platform may not detect zero-size allocation
|
|
* problems on other platforms.
|
|
*/
|
|
if (size == 0 || nmemb == 0)
|
|
return NULL;
|
|
return realloc(optr, size * nmemb);
|
|
}
|