Bluetooth: fix locking in hci_conn_request_evt() with HCI_PROTO_DEFER

[ Upstream commit 5c7209a ]

When protocol sets HCI_PROTO_DEFER, hci_conn_request_evt() calls
hci_connect_cfm(conn) without hdev->lock. Generally hci_connect_cfm()
assumes it is held, and if conn is deleted concurrently -> UAF.

Only SCO and ISO set HCI_PROTO_DEFER and only for defer setup listen,
and HCI_EV_CONN_REQUEST is not generated for ISO.  In the non-deferred
listening socket code paths, hci_connect_cfm(conn) is called with
hdev->lock held.

Fix by holding the lock.

Fixes: 70c4642 ("Bluetooth: Refactor connection request handling")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: pv

net/bluetooth/hci_event.c

@@ -3284,8 +3284,6 @@ static void hci_conn_request_evt(struct hci_dev *hdev, void *data,
 
 	memcpy(conn->dev_class, ev->dev_class, 3);
 
-	hci_dev_unlock(hdev);
-
 	if (ev->link_type == ACL_LINK ||
 	    (!(flags & HCI_PROTO_DEFER) && !lmp_esco_capable(hdev))) {
 		struct hci_cp_accept_conn_req cp;
@@ -3319,7 +3317,6 @@ static void hci_conn_request_evt(struct hci_dev *hdev, void *data,
 		hci_connect_cfm(conn, 0);
 	}
 
-	return;
 unlock:
 	hci_dev_unlock(hdev);
 }