Bluetooth: Fix RFCOMM usage of in-kernel L2CAP sockets

The CID value of L2CAP sockets need to be set to zero. All userspace
applications do this via memset() on the sockaddr_l2 structure. The
RFCOMM implementation uses in-kernel L2CAP sockets and so it has to
make sure that l2_cid is set to zero.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/rfcomm/core.c

@@ -658,6 +658,7 @@ static struct rfcomm_session *rfcomm_session_create(bdaddr_t *src, bdaddr_t *dst
 	bacpy(&addr.l2_bdaddr, src);
 	addr.l2_family = AF_BLUETOOTH;
 	addr.l2_psm    = 0;
+	addr.l2_cid    = 0;
 	*err = kernel_bind(sock, (struct sockaddr *) &addr, sizeof(addr));
 	if (*err < 0)
 		goto failed;
@@ -679,6 +680,7 @@ static struct rfcomm_session *rfcomm_session_create(bdaddr_t *src, bdaddr_t *dst
 	bacpy(&addr.l2_bdaddr, dst);
 	addr.l2_family = AF_BLUETOOTH;
 	addr.l2_psm    = htobs(RFCOMM_PSM);
+	addr.l2_cid    = 0;
 	*err = kernel_connect(sock, (struct sockaddr *) &addr, sizeof(addr), O_NONBLOCK);
 	if (*err == 0 || *err == -EINPROGRESS)
 		return s;
@@ -1919,6 +1921,7 @@ static int rfcomm_add_listener(bdaddr_t *ba)
 	bacpy(&addr.l2_bdaddr, ba);
 	addr.l2_family = AF_BLUETOOTH;
 	addr.l2_psm    = htobs(RFCOMM_PSM);
+	addr.l2_cid    = 0;
 	err = kernel_bind(sock, (struct sockaddr *) &addr, sizeof(addr));
 	if (err < 0) {
 		BT_ERR("Bind failed %d", err);