smb/server: fix potential null-ptr-deref of lease_ctx_info in smb2_open()

commit 4e8771a3666c8f216eefd6bd2fd50121c6c437db upstream.

null-ptr-deref will occur when (req_op_level == SMB2_OPLOCK_LEVEL_LEASE)
and parse_lease_state() return NULL.

Fix this by check if 'lease_ctx_info' is NULL.

Additionally, remove the redundant parentheses in
parse_durable_handle_context().

Signed-off-by: ChenXiaoSong <[email protected]>
Signed-off-by: Steve French <[email protected]>
[ Drop the parentheses clean-up since the parentheses was introduced by
  c8efcc786146 ("ksmbd: add support for durable handles v1/v2") in v6.9
  Minor context change fixed ]
Signed-off-by: Jianqi Ren <[email protected]>
Signed-off-by: He Zhe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: ChenXiaoSong

fs/smb/server/oplock.c

@@ -1515,7 +1515,7 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
  * @open_req:	buffer containing smb2 file open(create) request
  * @is_dir:	whether leasing file is directory
  *
- * Return:  oplock state, -ENOENT if create lease context not found
+ * Return: allocated lease context object on success, otherwise NULL
  */
 struct lease_ctx_info *parse_lease_state(void *open_req, bool is_dir)
 {

fs/smb/server/smb2pdu.c

@@ -3243,7 +3243,7 @@ int smb2_open(struct ksmbd_work *work)
 			goto err_out1;
 		}
 	} else {
-		if (req_op_level == SMB2_OPLOCK_LEVEL_LEASE) {
+		if (req_op_level == SMB2_OPLOCK_LEVEL_LEASE && lc) {
 			/*
 			 * Compare parent lease using parent key. If there is no
 			 * a lease that has same parent key, Send lease break