Bluetooth: use correct lock to prevent UAF of hdev object

stable inclusion
from linux-4.19.194
commit 2b9e9c2ed0f1910b5201c5d37b355b60201df415
CVE: CVE-2021-3573

--------------------------------

commit e305509e678b3a4af2b3cfd410f409f7cdaabb52 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

net/bluetooth/hci_sock.c

@@ -755,7 +755,7 @@ 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;
@@ -764,7 +764,7 @@ 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);
 	}