net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree()

commit 430ac66eb4c5b5c4eb846b78ebf65747510b30f1 upstream.

The patch adds the flush in p9_mux_poll_stop() as it the function used by
p9_conn_destroy(), in turn called by p9_fd_close() to stop the async
polling associated with the data regarding the connection.

Link: http://lkml.kernel.org/r/20180720092730.27104-1-tomasbortoli@gmail.com
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com
To: Eric Van Hensbergen <ericvh@gmail.com>
To: Ron Minnich <rminnich@sandia.gov>
To: Latchesar Ionkov <lucho@ionkov.net>
Cc: Yiwen Jiang <jiangyiwen@huwei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 7bc2208b6cc4c445286c20e01d9911ac9e75b9b2..f8dafa8fa70b39f1bcf3801089d0b754c4e6f6e6 100644 (file)
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -181,6 +181,8 @@ static void p9_mux_poll_stop(struct p9_conn *m)
        spin_lock_irqsave(&p9_poll_lock, flags);
        list_del_init(&m->poll_pending_link);
        spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+       flush_work(&p9_poll_work);
 }
 
 /**