netdev - Re: [PATCH] sctp: account stream padding length for reconf chunk

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Message-ID: <YWb7tFDwitBYSaXO@t14s.localdomain>
Date:   Wed, 13 Oct 2021 12:31:00 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Eiichi Tsukata <eiichi.tsukata@...anix.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] sctp: account stream padding length for reconf chunk

On Tue, Oct 12, 2021 at 12:17:08AM +0000, Eiichi Tsukata wrote:
> Hi Marcelo
> 
> > On Oct 11, 2021, at 22:15, Marcelo Ricardo Leitner <marcelo.leitner@...il.com> wrote:
> > 
> > 
> ...
> > 
> > So if stream_num was originally 1, stream_len would be 2, and with
> > padding, 4. Here, nums would be 2 then, and not 1. The padding gets
> > accounted as if it was payload.
> > 
> > IOW, the patch is making the padding part of the parameter data by
> > adding it to the header as well. SCTP padding works by having it in
> > between them, and not inside them.
> > 
> > This other approach avoids this issue by adding the padding only when
> > allocating the packet. It (ab)uses the fact that inreq and outreq are
> > already aligned to 4 bytes. Eiichi, can you please give it a go?
> > 
> > 
> 
> Thanks, I understood. I’ve tested your diff with my reproducer and it certainly works.
> Your diff looks good to me.

Cool, thanks. I'm running a couple more tests on it and will submit it
on your behalf by EOD if all goes well.

Regards,
Marcelo