diff options
| author | NeilBrown <neilb@suse.de> | 2022-03-08 05:42:17 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-15 15:17:58 +0300 |
| commit | 1cfeeeee8cf007a65a264e414ee0e5a4815550f4 (patch) | |
| tree | 5ae560f4eed90cc1755887a14e8e75cd1755899a | |
| parent | 1a1e73e9add747671b1e6828500459695bd8c1d2 (diff) | |
| download | linux-1cfeeeee8cf007a65a264e414ee0e5a4815550f4.tar.xz | |
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>
| -rw-r--r-- | net/sunrpc/xprt.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 93b6afd28405..8ac579778e48 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -2006,7 +2006,14 @@ static void xprt_destroy(struct rpc_xprt *xprt) */ wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE); + /* + * xprt_schedule_autodisconnect() can run after XPRT_LOCKED + * is cleared. We use ->transport_lock to ensure the mod_timer() + * can only run *before* del_time_sync(), never after. + */ + spin_lock(&xprt->transport_lock); del_timer_sync(&xprt->timer); + spin_unlock(&xprt->transport_lock); /* * Destroy sockets etc from the system workqueue so they can |