libceph: gracefully handle large reply messages from the mon

We preallocate a few of the message types we get back from the mon.  If we
get a larger message than we are expecting, fall back to trying to allocate
a new one instead of blindly using the one we have.

CC: stable@vger.kernel.org
Signed-off-by: Sage Weil <sage@redhat.com>
Reviewed-by: Ilya Dryomov <ilya.dryomov@inktank.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 067d3af2eaf6..61fcfc304f68 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -1181,7 +1181,15 @@ static struct ceph_msg *mon_alloc_msg(struct ceph_connection *con,
         if (!m) {
                 pr_info("alloc_msg unknown type %d\n", type);
                 *skip = 1;
+        } else if (front_len > m->front_alloc_len) {
+                pr_warning("mon_alloc_msg front %d > prealloc %d (%u#%llu)\n",
+                           front_len, m->front_alloc_len,
+                           (unsigned int)con->peer_name.type,
+                           le64_to_cpu(con->peer_name.num));
+                ceph_msg_put(m);
+                m = ceph_msg_new(type, front_len, GFP_NOFS, false);
         }
+
         return m;
 }