[PATCH 6.1 246/303] ksmbd: conn lock to serialize smb2 negotiate

6.1-stable review patch.  If anyone has any objections, please let me know.

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

From: Namjae Jeon <[email protected]>

[ Upstream commit fe4ed2f09b492e3507615a053814daa8fafdecb1 ]

If client send parallel smb2 negotiate request on same connection,
ksmbd_conn can be racy. smb2 negotiate handling that are not
performance-related can be serialized with conn lock.

Signed-off-by: Namjae Jeon <[email protected]>
Signed-off-by: Steve French <[email protected]>
Stable-dep-of: cb469993b3a6 ("ksmbd: reject repeated SMB2 NEGOTIATE requests")
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 fs/smb/server/smb2pdu.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -1126,6 +1126,7 @@ int smb2_handle_negotiate(struct ksmbd_w
 		return rc;
 	}
 
+	ksmbd_conn_lock(conn);
 	smb2_buf_len = get_rfc1002_len(work->request_buf);
 	smb2_neg_size = offsetof(struct smb2_negotiate_req, Dialects);
 	if (smb2_neg_size > smb2_buf_len) {
@@ -1275,6 +1276,7 @@ int smb2_handle_negotiate(struct ksmbd_w
 	ksmbd_conn_set_need_negotiate(conn);
 
 err_out:
+	ksmbd_conn_unlock(conn);
 	if (rc)
 		rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES;