ksmbd: fix race condition from parallel smb2 logoff requests

If parallel smb2 logoff requests come in before closing door, running
request count becomes more than 1 even though connection status is set to
KSMBD_SESS_NEED_RECONNECT. It can't get condition true, and sleep forever.
This patch fix race condition problem by returning error if connection
status was already set to KSMBD_SESS_NEED_RECONNECT.

Reported-by: luosili <rootlab@huawei.com>
Signed-off-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 b9d6e8e451ba215b6bb9c4692fd59f2714954e44..e774c9855f7ffedec3f72d7b8015b96a72aa530c 100644 (file)
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2164,17 +2164,17 @@ int smb2_session_logoff(struct ksmbd_work *work)
 
        ksmbd_debug(SMB, "request\n");
 
-       sess_id = le64_to_cpu(req->hdr.SessionId);
-
-       rsp->StructureSize = cpu_to_le16(4);
-       err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_logoff_rsp));
-       if (err) {
-               rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;
+       ksmbd_conn_lock(conn);
+       if (!ksmbd_conn_good(conn)) {
+               ksmbd_conn_unlock(conn);
+               rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED;
                smb2_set_err_rsp(work);
-               return err;
+               return -ENOENT;
        }
-
+       sess_id = le64_to_cpu(req->hdr.SessionId);
        ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_RECONNECT);
+       ksmbd_conn_unlock(conn);
+
        ksmbd_close_session_fds(work);
        ksmbd_conn_wait_idle(conn, sess_id);
 
@@ -2196,6 +2196,14 @@ int smb2_session_logoff(struct ksmbd_work *work)
        ksmbd_free_user(sess->user);
        sess->user = NULL;
        ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_NEGOTIATE);
+
+       rsp->StructureSize = cpu_to_le16(4);
+       err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_logoff_rsp));
+       if (err) {
+               rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;
+               smb2_set_err_rsp(work);
+               return err;
+       }
        return 0;
 }