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

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[ Upstream commit e052d05402 ]

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>
This commit is contained in:
Oleksij Rempel 2020-08-07 12:52:00 +02:00 committed by Greg Kroah-Hartman
parent 3803312a3c
commit 021a98a878
1 changed files with 14 additions and 1 deletions
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15
net/can/j1939/transport.c
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@ -1803,7 +1803,20 @@ static void j1939_xtp_rx_dat_one(struct j1939_session *session,
}
tpdat = se_skb->data;
memcpy(&tpdat[offset], &dat[1], nbytes);
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++;