From: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200807105200.26441-6-o.rempel@xxxxxxxxxxxxxx Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/can/j1939/transport.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 9f99af5b0b11e..3e9c377b0dcce 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -1769,7 +1769,20 @@ 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++; -- 2.25.1
