[ 10/24] libceph: avoid NULL kref_put when osd reset races with alloc_msg

Greg Kroah-Hartman
2012-11-02T17:07:49Z

From: Sage Weil <sage@inktank.com>

commit 9bd952615a42d7e2ce3fa2c632e808e804637a1a upstream.

The ceph_on_in_msg_alloc() method drops con->mutex while it allocates a
message. If that races with a timeout that resends a zillion messages and
resets the connection, and the ->alloc_msg() method returns a NULL message,
it will call ceph_msg_put(NULL) and BUG.

Fix by only calling put if msg is non-NULL.

Fixes http://tracker.newdream.net/issues/3142

Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/ceph/messenger.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2750,7 +2750,8 @@ static int ceph_con_in_msg_alloc(struct
msg = con->ops->alloc_msg(con, hdr, skip);
mutex_lock(&con->mutex);
if (con->state != CON_STATE_OPEN) {
- ceph_msg_put(msg);
+ if (msg)
+ ceph_msg_put(msg);
return -EAGAIN;
}
con->in_msg = msg;