From: Christian Lamparter <chunkeey@googlemail.com>
To: Jay Smith <jay@kentik.com>, Alan Curry <rlwinm@sdf.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
netdev@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
"davem@davemloft.net" <davem@davemloft.net>
Subject: Re: UDP wierdness around skb_copy_and_csum_datagram_msg()
Date: Fri, 30 Sep 2016 01:28:18 +0200 [thread overview]
Message-ID: <3897844.9kvF4Wy8aS@debian64> (raw)
In-Reply-To: <CAA3=++_6O69hcutQ_FmaivrR3UV-uKScyX8+iHOBV9kraizOFQ@mail.gmail.com>
On Wednesday, September 28, 2016 7:20:39 PM CEST Jay Smith wrote:
> Actually, on a little more searching of this list's archives, I think
> that this discussion: https://patchwork.kernel.org/patch/9260733/ is
> about exactly the same issue I've found, except from the TCP side. I'm
> cc'ing a few of the participants from that discussion.
>
> So is the patch proposed there (copying and restoring the entire
> iov_iter in skb_copy_and_csum_datagram_msg()) being considered as a
> fix?
>From Alan's post:
"My ugly patch fixes this in the most obvious way: make a local copy of
msg->msg_iter before the call to skb_copy_and_csum_datagram(), and copy
it back if the checksum is bad, just before goto csum_error;"
IMHO this meant that the patch is a proof of concept for his problem.
> If not, would an alternate one that concealed the save-and-restore logic
> inside iov_iter.c be more acceptable? I'd be happy to produce whatever's
> needed, or yield to someone with stronger feelings about where it should
> go...
Al Viro identified more inconsistencies within the error-paths that deal
with EFAULT in the whole area (in and around skb_copy_and_csum_datagram()).
As far as I can tell the original discussion about the data corruption
issue went off on a tangent and it is stuck in figuring out "How to handle
the errors in tcp_copy_to_iovec()".
As for fixing the issue: I'm happy to test and review patches.
The trouble is that nobody seem to be able to produce them...
Regards,
Christian
next prev parent reply other threads:[~2016-09-29 23:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-29 0:18 UDP wierdness around skb_copy_and_csum_datagram_msg() Jay Smith
2016-09-29 1:24 ` Eric Dumazet
2016-09-29 2:20 ` Jay Smith
2016-09-29 23:28 ` Christian Lamparter [this message]
2016-09-30 0:06 ` Eric Dumazet
2016-09-30 17:35 ` Jay Smith
2016-09-30 18:40 ` Christian Lamparter
2016-10-17 17:10 ` Jay Smith
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3897844.9kvF4Wy8aS@debian64 \
--to=chunkeey@googlemail.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=jay@kentik.com \
--cc=netdev@vger.kernel.org \
--cc=rlwinm@sdf.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.