Bluetooth: use correct lock to prevent UAF of hdev object

The hci_sock_dev_event() function will cleanup the hdev object for
sockets even if this object may still be in used within the
hci_sock_bound_ioctl() function, result in UAF vulnerability.

This patch replace the BH context lock to serialize these affairs
and prevent the race condition.
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_sock.c

@@ -762,7 +762,7 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event)
 		/* Detach sockets from device */
 		read_lock(&hci_sk_list.lock);
 		sk_for_each(sk, &hci_sk_list.head) {
-			bh_lock_sock_nested(sk);
+			lock_sock(sk);
 			if (hci_pi(sk)->hdev == hdev) {
 				hci_pi(sk)->hdev = NULL;
 				sk->sk_err = EPIPE;
@@ -771,7 +771,7 @@ void hci_sock_dev_event(struct hci_dev *hdev, int event)
 
 				hci_dev_put(hdev);
 			}
-			bh_unlock_sock(sk);
+			release_sock(sk);
 		}
 		read_unlock(&hci_sk_list.lock);
 	}