Bluetooth: Drop packets on ATT fixed channel on BR/EDR

The ATT fixed channel is only valid when using LE connections. On
BR/EDR it is required to go through L2CAP connection oriented
channel for ATT.

Drop ATT packets when they are received on a BR/EDR connection.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

net/bluetooth/l2cap_core.c

@@ -6431,8 +6431,12 @@ drop:
 static void l2cap_att_channel(struct l2cap_conn *conn,
 			      struct sk_buff *skb)
 {
+	struct hci_conn *hcon = conn->hcon;
 	struct l2cap_chan *chan;
 
+	if (hcon->type != LE_LINK)
+		goto drop;
+
 	chan = l2cap_global_chan_by_scid(BT_CONNECTED, L2CAP_CID_ATT,
 					 conn->src, conn->dst);
 	if (!chan)