From ac125d93ae92d9a55db35c56e860658b53208f01 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Tue, 5 Jul 2022 11:16:24 +0000 Subject: [PATCH 1/2] cifs: fix race condition with delayed threads On failure to create a new channel, first cancel the delayed threads, which could try to search for this channel, and not find it. The other option was to put the tcp session for the channel first, before decrementing chan_count. But that would leave a reference to the tcp session, when it has been freed already. So going with the former option and cancelling the delayed works first, before rolling back the channel. Fixes: aa45dadd34e4 ("cifs: change iface_list from array to sorted linked list") Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/cifs/sess.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index b85718f32b53..02c8b2906196 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -474,6 +474,14 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses, out: if (rc && chan->server) { + /* + * we should avoid race with these delayed works before we + * remove this channel + */ + cancel_delayed_work_sync(&chan->server->echo); + cancel_delayed_work_sync(&chan->server->resolve); + cancel_delayed_work_sync(&chan->server->reconnect); + spin_lock(&ses->chan_lock); /* we rely on all bits beyond chan_count to be clear */ cifs_chan_clear_need_reconnect(ses, chan->server); @@ -484,10 +492,9 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses, */ WARN_ON(ses->chan_count < 1); spin_unlock(&ses->chan_lock); - } - if (rc && chan->server) cifs_put_tcp_session(chan->server, 0); + } return rc; } -- 2.34.1