Bluetooth: MGMT: Add error handling to pair_device()

hci_conn_params_add() never checks for a NULL value and could lead to a NULL
pointer dereference causing a crash.

Fixed by adding error handling in the function.

Cc: Stable <stable@kernel.org>
Fixes: 5157b8a5 ("Bluetooth: Fix initializing conn_params in scan phase")
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Reported-by: Yiwei Zhang <zhan4630@purdue.edu>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/mgmt.c

@@ -3456,6 +3456,10 @@ static int pair_device(struct sock *sk, struct hci_dev *hdev, void *data,
 		 * will be kept and this function does nothing.
 		 */
 		p = hci_conn_params_add(hdev, &cp->addr.bdaddr, addr_type);
+		if (!p) {
+			err = -EIO;
+			goto unlock;
+		}
 
 		if (p->auto_connect == HCI_AUTO_CONN_EXPLICIT)
 			p->auto_connect = HCI_AUTO_CONN_DISABLED;