netdev - Re: [PATCH net 3/3] can: j1939: j1939_tp_cmd_recv(): check the dst address of TP.CM

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Message-ID: <20211022102858.GC20681@pengutronix.de>
Date:   Fri, 22 Oct 2021 12:28:58 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Zhang Changzhong <zhangchangzhong@...wei.com>
Cc:     Robin van der Gracht <robin@...tonic.nl>,
        Oleksij Rempel <linux@...pel-privat.de>, kernel@...gutronix.de,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 3/3] can: j1939: j1939_tp_cmd_recv(): check the dst
 address of TP.CM_BAM

On Thu, Oct 21, 2021 at 10:04:17PM +0800, Zhang Changzhong wrote:
> The TP.CM_BAM message must be sent to the global address [1], so add a
> check to drop TP.CM_BAM sent to a non-global address.
> 
> Without this patch, the receiver will treat the following packets as
> normal RTS/CTS tranport:
> 18EC0102#20090002FF002301
> 18EB0102#0100000000000000
> 18EB0102#020000FFFFFFFFFF
> 
> [1] SAE-J1939-82 2015 A.3.3 Row 1.
> 
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
> ---
>  net/can/j1939/transport.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index 2efa606..93ec0c3 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -2019,6 +2019,8 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
>  		extd = J1939_ETP;
>  		fallthrough;
>  	case J1939_TP_CMD_BAM:
> +		if (!j1939_cb_is_broadcast(skcb))

Please add here netdev_err_once("with some message"), we need to know if
some MCU makes bad things.

> +			return;
>  		fallthrough;
>  	case J1939_TP_CMD_RTS:
>  		if (skcb->addr.type != extd)
> -- 
> 2.9.5
> 
> 

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