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introduce SIZE_MAX

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ULONG_MAX is often used to check for integer overflow when calculating
allocation size.  While ULONG_MAX happens to work on most systems, there
is no guarantee that `size_t' must be the same size as `long'.

This patch introduces SIZE_MAX, the maximum value of `size_t', to improve
portability and readability for allocation size validation.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Acked-by: Alex Elder <elder@dreamhost.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Xi Wang 2012-05-31 16:26:04 -07:00 committed by Linus Torvalds
parent 15837294d4
commit a3860c1c5d
4 changed files with 5 additions and 4 deletions
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2
fs/ceph/snap.c
View File

@ -331,7 +331,7 @@ static int build_snap_context(struct ceph_snap_realm *realm)
/* alloc new snap context */
err = -ENOMEM;
if (num > (ULONG_MAX - sizeof(*snapc)) / sizeof(u64))
if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
goto fail;
snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS);
if (!snapc)

4
include/drm/drm_mem_util.h
View File

@ -31,7 +31,7 @@
static __inline__ void *drm_calloc_large(size_t nmemb, size_t size)
{
if (size != 0 && nmemb > ULONG_MAX / size)
if (size != 0 && nmemb > SIZE_MAX / size)
return NULL;
if (size * nmemb <= PAGE_SIZE)
@ -44,7 +44,7 @@ static __inline__ void *drm_calloc_large(size_t nmemb, size_t size)
/* Modeled after cairo's malloc_ab, it's like calloc but without the zeroing. */
static __inline__ void *drm_malloc_ab(size_t nmemb, size_t size)
{
if (size != 0 && nmemb > ULONG_MAX / size)
if (size != 0 && nmemb > SIZE_MAX / size)
return NULL;
if (size * nmemb <= PAGE_SIZE)

1
include/linux/kernel.h
View File

@ -35,6 +35,7 @@
#define LLONG_MAX ((long long)(~0ULL>>1))
#define LLONG_MIN (-LLONG_MAX - 1)
#define ULLONG_MAX (~0ULL)
#define SIZE_MAX (~(size_t)0)
#define STACK_MAGIC 0xdeadbeef

2
include/linux/slab.h
View File

@ -242,7 +242,7 @@ size_t ksize(const void *);
*/
static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
{
if (size != 0 && n > ULONG_MAX / size)
if (size != 0 && n > SIZE_MAX / size)
return NULL;
return __kmalloc(n * size, flags);
}