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authorXi Wang <xi.wang@gmail.com>2012-05-31 16:26:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 17:49:26 -0700
commita3860c1c5dd1137db23d7786d284939c5761d517 (patch)
tree48d688c6c391ef45f79bdd60815450ca06c5cc1a
parent15837294d4ce717f69942f7366e99d4d1d3d9923 (diff)
introduce SIZE_MAX
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>
-rw-r--r--fs/ceph/snap.c2
-rw-r--r--include/drm/drm_mem_util.h4
-rw-r--r--include/linux/kernel.h1
-rw-r--r--include/linux/slab.h2
4 files changed, 5 insertions, 4 deletions
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index f04c0961f99..e5206fc7656 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -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)
diff --git a/include/drm/drm_mem_util.h b/include/drm/drm_mem_util.h
index 6bd325fedc8..19a240446fc 100644
--- a/include/drm/drm_mem_util.h
+++ b/include/drm/drm_mem_util.h
@@ -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)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index ec55a3c8ba7..e07f5e0c5df 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -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
diff --git a/include/linux/slab.h b/include/linux/slab.h
index a595dce6b0c..67d5d94b783 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -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);
}