[PATCH 3.2 89/94] introduce SIZE_MAX
From: Ben Hutchings <hidden>
Date: 2014-08-04 17:10:51
Also in:
lkml
3.2.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Xi Wang <xi.wang@gmail.com> commit a3860c1c5dd1137db23d7786d284939c5761d517 upstream. 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 <redacted> Cc: David Airlie <redacted> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <redacted> --- fs/ceph/snap.c | 2 +- include/drm/drm_mem_util.h | 4 ++-- include/linux/kernel.h | 1 + include/linux/slab.h | 2 +- 4 files changed, 5 insertions(+), 4 deletions(-)
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c@@ -331,7 +331,7 @@ static int build_snap_context(struct cep /* 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) --- 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 /* 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) --- a/include/linux/kernel.h +++ b/include/linux/kernel.h
@@ -34,6 +34,7 @@ #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 --- 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); }