linux-kernel - Re: [PATCH] j1939: fix unable to send messages with data length zero

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z4jFYFLbIyUzA62W@pengutronix.de>
Date: Thu, 16 Jan 2025 09:37:52 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Alexander Hölzl <alexander.hoelzl@....net>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>, robin@...tonic.nl,
	socketcan@...tkopp.net, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, corbet@....net,
	kernel@...gutronix.de, linux-can@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] j1939: fix unable to send messages with data length zero

Hi Alexander,

On Tue, Jan 07, 2025 at 06:17:13PM +0100, Alexander Hölzl wrote:
> On 1/7/25 14:48, Marc Kleine-Budde wrote:
> > On 07.01.2025 14:32:17, Alexander Hölzl wrote:
> > > The J1939 standard requires the transmission of messages of length 0.
> > > For example the proprietary messages are specified with a data length
> > > of 0 to 1785. The transmission of such messages was not possible.
> > > Sending such a message resulted in no error being returned but no
> > > corresponding can frame being generated.
> > 
> > What does your patch do? Please describe it here.
> > 
> > Marc
> The patch enables the transmission of zero length J1939 messages.
> In order to facilitate this two changes were necessary.
> 
> First when the transmission of a new message is requested from userspace
> the message is segmented in j1939_sk_send_loop. The segmentation did
> account for zero length messages and terminated immediately without
> queuing the corresponding skb.
> 
> Second when selecting the next skb in j1939_session_skb_get_by_offset to
> transmit for a session, it was not checked that there now might be a
> zero length skb in the queue.
> 
> Also as this is my first real patch I'm submitting please don't hesitate
> to tell me if I'm doing something wrong.

Please resend this patch with updated, more detailed, commit message.

> > > Signed-off-by: Alexander Hölzl <alexander.hoelzl@....net>

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

Thank you!
-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |