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Date:   Wed, 3 Nov 2021 14:26:07 +0100
From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Zhang Changzhong <zhangchangzhong@huawei.com>
Cc:     Robin van der Gracht <robin@protonic.nl>,
        Oleksij Rempel <linux@rempel-privat.de>, kernel@pengutronix.de,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v2 3/3] can: j1939: j1939_tp_cmd_recv(): check the
 dst address of TP.CM_BAM
Message-ID: <20211103132607.GM20681@pengutronix.de>
References: <1635431907-15617-1-git-send-email-zhangchangzhong@huawei.com>
 <1635431907-15617-4-git-send-email-zhangchangzhong@huawei.com>
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On Thu, Oct 28, 2021 at 10:38:27PM +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@huawei.com>

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

> ---
>  net/can/j1939/transport.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
> index 05eb3d0..a271688 100644
> --- a/net/can/j1939/transport.c
> +++ b/net/can/j1939/transport.c
> @@ -2023,6 +2023,11 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
>  		extd = J1939_ETP;
>  		fallthrough;
>  	case J1939_TP_CMD_BAM:
> +		if (cmd == J1939_TP_CMD_BAM && !j1939_cb_is_broadcast(skcb)) {
> +			netdev_err_once(priv->ndev, "%s: BAM to unicast (%02x), ignoring!\n",
> +					__func__, skcb->addr.sa);
> +			return;
> +		}
>  		fallthrough;
>  	case J1939_TP_CMD_RTS:
>  		if (skcb->addr.type != extd)
> -- 
> 2.9.5
> 
> 

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