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SubjectRe: [PATCH net] can: j1939: j1939_xtp_rx_rts_session_new(): abort TP less than 9 bytes
On Thu, Oct 14, 2021 at 05:26:40PM +0800, Zhang Changzhong wrote:
> The receiver should abort TP if 'total message size' in TP.CM_RTS and
> TP.CM_BAM is less than 9 or greater than 1785 [1], but currently the
> j1939 stack only checks the upper bound and the receiver will accept the
> following broadcast message:
> vcan1 18ECFF00 [8] 20 08 00 02 FF 00 23 01
> vcan1 18EBFF00 [8] 01 00 00 00 00 00 00 00
> vcan1 18EBFF00 [8] 02 00 FF FF FF FF FF FF
>
> This patch adds check for the lower bound and abort illegal TP.
>
> [1] SAE-J1939-82 A.3.4 Row 2 and A.3.6 Row 6.
>
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Thank you!

> ---
> net/can/j1939/j1939-priv.h | 1 +
> net/can/j1939/transport.c | 2 ++
> 2 files changed, 3 insertions(+)
>
> diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h
> index f6df208..16af1a7 100644
> --- a/net/can/j1939/j1939-priv.h
> +++ b/net/can/j1939/j1939-priv.h
> @@ -330,6 +330,7 @@ int j1939_session_activate(struct j1939_session *session);
> void j1939_tp_schedule_txtimer(struct j1939_session *session, int msec);
> void j1939_session_timers_cancel(struct j1939_session *session);
>
> +#define J1939_MIN_TP_PACKET_SIZE 9
> #define J1939_MAX_TP_PACKET_SIZE (7 * 0xff)
> #define J1939_MAX_ETP_PACKET_SIZE (7 * 0x00ffffff)
>
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index bb5c4b8..b685d31 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -1609,6 +1609,8 @@ j1939_session *j1939_xtp_rx_rts_session_new(struct j1939_priv *priv,
> abort = J1939_XTP_ABORT_FAULT;
> else if (len > priv->tp_max_packet_size)
> abort = J1939_XTP_ABORT_RESOURCE;
> + else if (len < J1939_MIN_TP_PACKET_SIZE)
> + abort = J1939_XTP_ABORT_FAULT;
> }
>
> if (abort != J1939_XTP_NO_ABORT) {
> --
> 2.9.5
>
>

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