NeilBrown 518a7d6be1 SUNRPC: avoid race between mod_timer() and del_timer_sync()
commit 3848e96edf4788f772d83990022fa7023a233d83 upstream.

xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync().
Both xprt_unlock_connect() and xprt_release() call
 ->release_xprt()
which drops XPRT_LOCKED and *then* xprt_schedule_autodisconnect()
which calls mod_timer().

This may result in mod_timer() being called *after* del_timer_sync().
When this happens, the timer may fire long after the xprt has been freed,
and run_timer_softirq() will probably crash.

The pairing of ->release_xprt() and xprt_schedule_autodisconnect() is
always called under ->transport_lock.  So if we take ->transport_lock to
call del_timer_sync(), we can be sure that mod_timer() will run first
(if it runs at all).

Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-08 14:22:52 +02:00
..
2022-03-11 12:22:36 +01:00
2021-06-30 15:51:09 -07:00
2021-06-29 11:28:21 -07:00
2021-07-29 15:06:49 +01:00
2021-07-29 15:06:49 +01:00