ksmbd: fix use-after-free in session logoff

The sess->user object can currently be in use by another thread, for
example if another connection has sent a session setup request to
bind to the session being free'd. The handler for that connection could
be in the smb2_sess_setup function which makes use of sess->user.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Heelan <seanheelan@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index acc05657cfc72ad38160bad711c8499997c38632..46aa082457424b5e3997446a2f19ce200d80c0e6 100644 (file)
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2249,10 +2249,6 @@ int smb2_session_logoff(struct ksmbd_work *work)
        sess->state = SMB2_SESSION_EXPIRED;
        up_write(&conn->session_lock);
 
-       if (sess->user) {
-               ksmbd_free_user(sess->user);
-               sess->user = NULL;
-       }
        ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_SETUP);
 
        rsp->StructureSize = cpu_to_le16(4);