From: Yan, Zheng <zheng.z.yan@intel.com>
Date: Thu, 20 Sep 2012 09:42:25 +0000 (+0800)
Subject: ceph: Fix oops when handling mdsmap that decreases max_mds
X-Git-Tag: v3.4.20~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=73bba6fc44591587254fec8e867a99b5a2a28ba7;p=platform%2Fkernel%2Flinux-stable.git

ceph: Fix oops when handling mdsmap that decreases max_mds

(cherry picked from commit 3e8f43a089f06279c5f76a9ccd42578eebf7bfa5)

When i >= newmap->m_max_mds, ceph_mdsmap_get_addr(newmap, i) return
NULL. Passing NULL to memcmp() triggers oops.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 5ac6434..7f1682d 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2634,7 +2634,8 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 		     ceph_mdsmap_is_laggy(newmap, i) ? " (laggy)" : "",
 		     session_state_name(s->s_state));
 
-		if (memcmp(ceph_mdsmap_get_addr(oldmap, i),
+		if (i >= newmap->m_max_mds ||
+		    memcmp(ceph_mdsmap_get_addr(oldmap, i),
 			   ceph_mdsmap_get_addr(newmap, i),
 			   sizeof(struct ceph_entity_addr))) {
 			if (s->s_state == CEPH_MDS_SESSION_OPENING) {