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authorXi Wang <xi.wang@gmail.com>2012-02-16 11:56:29 -0500
committerAlex Elder <elder@dreamhost.com>2012-03-22 10:47:45 -0500
commit80834312a4da1405a9bc788313c67643de6fcb4c (patch)
tree46fdff81b144f9307a4361f943b7f0fa4d7f1341
parent64486697771cbe219fffcb5c8e2ed9ca4fdf086c (diff)
downloadlinux-80834312a4da1405a9bc788313c67643de6fcb4c.tar.bz2
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 <xi.wang@gmail.com> Signed-off-by: Sage Weil <sage@newdream.net>
-rw-r--r--fs/ceph/snap.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index a559c80f127a..f04c0961f993 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)