linux-kernel - Re: [PATCH net 2/3] can: j1939: j1939_can_recv(): ignore messages with invalid source address

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Date:   Fri, 22 Oct 2021 12:23:06 +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>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-can@...r.kernel.org
Subject: Re: [PATCH net 2/3] can: j1939: j1939_can_recv(): ignore messages
 with invalid source address

On Thu, Oct 21, 2021 at 10:04:16PM +0800, Zhang Changzhong wrote:
> According to SAE-J1939-82 2015 (A.3.6 Row 2), a receiver should never
> send TP.CM_CTS to the global address, so we can add a check in
> j1939_can_recv() to drop messages with invalid source address.
> 
> Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>

NACK. This will break Address Claiming, where first message is SA == 0xff

> ---
>  net/can/j1939/main.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
> index 08c8606..4f1e4bb 100644
> --- a/net/can/j1939/main.c
> +++ b/net/can/j1939/main.c
> @@ -75,6 +75,10 @@ static void j1939_can_recv(struct sk_buff *iskb, void *data)
>  	skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
>  	/* set default message type */
>  	skcb->addr.type = J1939_TP;
> +	if (!j1939_address_is_valid(skcb->addr.sa))
> +		/* ignore messages whose sa is broadcast address */
> +		goto done;
> +
>  	if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
>  		/* Type 1: with destination address */
>  		skcb->addr.da = skcb->addr.pgn;
> -- 
> 2.9.5
> 
> 
> 

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