[bug report] Bluetooth: Fix not checking MGMT cmd pending queue

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Brian Gix,

The patch 275f3f648702: "Bluetooth: Fix not checking MGMT cmd pending
queue" from Mar 1, 2022, leads to the following Smatch static checker
warning:

	net/bluetooth/mgmt.c:1587 mgmt_set_connectable_complete()
	warn: variable dereferenced before check 'cmd' (see line 1579)

net/bluetooth/mgmt.c
    1564 static void mgmt_set_connectable_complete(struct hci_dev *hdev, void *data,
    1565                                           int err)
    1566 {
    1567         struct mgmt_pending_cmd *cmd = data;
    1568 
    1569         bt_dev_dbg(hdev, "err %d", err);
    1570 
    1571         /* Make sure cmd still outstanding. */
    1572         if (cmd != pending_find(MGMT_OP_SET_CONNECTABLE, hdev))
    1573                 return;
    1574 
    1575         hci_dev_lock(hdev);
    1576 
    1577         if (err) {
    1578                 u8 mgmt_err = mgmt_status(err);
    1579                 mgmt_cmd_status(cmd->sk, cmd->index, cmd->opcode, mgmt_err);
                                         ^^^^^^^

    1580                 goto done;
    1581         }
    1582 
    1583         send_settings_rsp(cmd->sk, MGMT_OP_SET_CONNECTABLE, hdev);
    1584         new_settings(hdev, cmd->sk);
                                    ^^^^^^^
Dereferences.

    1585 
    1586 done:
--> 1587         if (cmd)
                     ^^^
The patch adds a new NULL check but the pointer has already been
dereferenced.

    1588                 mgmt_pending_remove(cmd);
    1589 
    1590         hci_dev_unlock(hdev);
    1591 }

regards,
dan carpenter