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

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 <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/oplock.c

@@ -1510,7 +1510,7 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
  * parse_lease_state() - parse lease context containted in file open request
  * @open_req:	buffer containing smb2 file open(create) request
  *
- * 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)
 {

fs/smb/server/smb2pdu.c

@@ -2770,8 +2770,8 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				}
 			}
 
-			if (((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
-			     req_op_level == SMB2_OPLOCK_LEVEL_BATCH)) {
+			if ((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
+			    req_op_level == SMB2_OPLOCK_LEVEL_BATCH) {
 				dh_info->CreateGuid =
 					durable_v2_blob->CreateGuid;
 				dh_info->persistent =
@@ -2791,8 +2791,8 @@ static int parse_durable_handle_context(struct ksmbd_work *work,
 				goto out;
 			}
 
-			if (((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
-			     req_op_level == SMB2_OPLOCK_LEVEL_BATCH)) {
+			if ((lc && (lc->req_state & SMB2_LEASE_HANDLE_CACHING_LE)) ||
+			    req_op_level == SMB2_OPLOCK_LEVEL_BATCH) {
 				ksmbd_debug(SMB, "Request for durable open\n");
 				dh_info->type = dh_idx;
 			}
@@ -3414,7 +3414,7 @@ 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) {
 			if (S_ISDIR(file_inode(filp)->i_mode)) {
 				lc->req_state &= ~SMB2_LEASE_WRITE_CACHING_LE;
 				lc->is_dir = true;