From 3232ba962ce31470feb5a1dd749b5c86b26d008b Mon Sep 17 00:00:00 2001 From: Xi Wang Date: Thu, 3 May 2012 15:44:13 +1000 Subject: [PATCH] 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 Acked-by: Alex Elder Cc: David Airlie Cc: Pekka Enberg Signed-off-by: Andrew Morton --- 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(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index f04c0961f993..e5206fc76562 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 6bd325fedc87..19a240446fca 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 645231c373c8..b795ee5cd208 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 a595dce6b0c7..67d5d94b783a 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); } -- 2.39.5