Commit 021a98a8 authored Aug 07, 2020 by Oleksij Rempel Committed by Greg Kroah-Hartman Sep 03, 2020

can: j1939: transport: j1939_xtp_rx_dat_one(): compare own packets to detect corruptions



[ Upstream commit e052d0540298bfe0f6cbbecdc7e2ea9b859575b2 ]

Since the stack relays on receiving own packets, it was overwriting own
transmit buffer from received packets.

At least theoretically, the received echo buffer can be corrupt or
changed and the session partner can request to resend previous data. In
this case we will re-send bad data.

With this patch we will stop to overwrite own TX buffer and use it for
sanity checking.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20200807105200.26441-6-o.rempel@pengutronix.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 3803312a

net/can/j1939/transport.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -1803,7 +1803,20 @@ static void j1939_xtp_rx_dat_one(struct j1939_session *session,
		}

		tpdat = se_skb->data;
		if (!session->transmission) {
		memcpy(&tpdat[offset], &dat[1], nbytes);
		} else {
		int err;

		err = memcmp(&tpdat[offset], &dat[1], nbytes);
		if (err)
		netdev_err_once(priv->ndev,
		"%s: 0x%p: Data of RX-looped back packet (%ph) doesn't match TX data (%ph)!\n",
		__func__, session,
		nbytes, &dat[1],
		nbytes, &tpdat[offset]);
		}

		if (packet == session->pkt.rx)
		session->pkt.rx++;