can: j1939: transport: j1939_xtp_rx_eoma_one(): Add sanity check for correct total message size

We were sending malformed EOMA with total message size set to 0. This
issue has been fixed in the previous patch.

In this patch a sanity check is added to the RX path and a error message
is displayed.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

net/can/j1939/transport.c

@@ -1273,9 +1273,27 @@ j1939_xtp_rx_abort(struct j1939_priv *priv, struct sk_buff *skb,
 static void
 j1939_xtp_rx_eoma_one(struct j1939_session *session, struct sk_buff *skb)
 {
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	const u8 *dat;
+	int len;
+
 	if (j1939_xtp_rx_cmd_bad_pgn(session, skb))
 		return;
 
+	dat = skb->data;
+
+	if (skcb->addr.type == J1939_ETP)
+		len = j1939_etp_ctl_to_size(dat);
+	else
+		len = j1939_tp_ctl_to_size(dat);
+
+	if (session->total_message_size != len) {
+		netdev_warn_once(session->priv->ndev,
+				 "%s: 0x%p: Incorrect size. Expected: %i; got: %i.\n",
+				 __func__, session, session->total_message_size,
+				 len);
+	}
+
 	netdev_dbg(session->priv->ndev, "%s: 0x%p\n", __func__, session);
 
 	session->pkt.tx_acked = session->pkt.total;