From 80834312a4da1405a9bc788313c67643de6fcb4c Mon Sep 17 00:00:00 2001 From: Xi Wang Date: Thu, 16 Feb 2012 11:56:29 -0500 Subject: [PATCH] ceph: fix overflow check in build_snap_context() The overflow check for a + n * b should be (n > (ULONG_MAX - a) / b), rather than (n > ULONG_MAX / b - a). Signed-off-by: Xi Wang Signed-off-by: Sage Weil --- fs/ceph/snap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index a559c80..f04c096 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(u64) - sizeof(*snapc)) + if (num > (ULONG_MAX - sizeof(*snapc)) / sizeof(u64)) goto fail; snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS); if (!snapc) -- 2.7.4