cifs: Fix oops due to uncleared server->smbd_conn in reconnect

stable inclusion
from stable-v5.10.166
commit e037baee16e0b9ace7e730888fcae9cec11daff2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I87FRA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e037baee16e0b9ace7e730888fcae9cec11daff2



--------------------------------

commit b7ab9161 upstream.

In smbd_destroy(), clear the server->smbd_conn pointer after freeing the
smbd_connection struct that it points to so that reconnection doesn't get
confused.

Fixes: 8ef130f9 ("CIFS: SMBD: Implement function to destroy a SMB Direct connection")
Cc: stable@vger.kernel.org
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Long Li <longli@microsoft.com>
Cc: Pavel Shilovsky <piastryyy@gmail.com>
Cc: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>