From: Rainer Weikusat <rweikusat@mobileactivedefense•com>
To: Jason Baron <jbaron@akamai•com>
Cc: Mathias Krause <minipli@googlemail•com>,
netdev@vger•kernel.org,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger•kernel.org>,
Eric Wong <normalperson@yhbt•net>,
Eric Dumazet <eric.dumazet@gmail•com>,
Rainer Weikusat <rweikusat@mobileactivedefense•com>,
Alexander Viro <viro@zeniv•linux.org.uk>,
Davide Libenzi <davidel@xmailserver•org>,
Davidlohr Bueso <dave@stgolabs•net>,
Olivier Mauras <olivier@mauras•ch>,
PaX Team <pageexec@freemail•hu>,
Linus Torvalds <torvalds@linux-foundation•org>,
"peterz\@infradead.org" <peterz@infradead•org>,
"davem\@davemloft.net" <davem@davemloft•net>
Subject: Re: List corruption on epoll_ctl(EPOLL_CTL_DEL) an AF_UNIX socket
Date: Thu, 01 Oct 2015 11:33:59 +0100 [thread overview]
Message-ID: <87oagiho88.fsf@doppelsaurus.mobileactivedefense.com> (raw)
In-Reply-To: <560C9CFE.6090509@akamai.com> (Jason Baron's message of "Wed, 30 Sep 2015 22:39:58 -0400")
Jason Baron <jbaron@akamai•com> writes:
> On 09/30/2015 01:54 AM, Mathias Krause wrote:
>> On 29 September 2015 at 21:09, Jason Baron <jbaron@akamai•com> wrote:
>>> However, if we call connect on socket 's', to connect to a new socket 'o2', we
>>> drop the reference on the original socket 'o'. Thus, we can now close socket
>>> 'o' without unregistering from epoll. Then, when we either close the ep
>>> or unregister 'o', we end up with this list corruption. Thus, this is not a
>>> race per se, but can be triggered sequentially.
>>
>> Sounds profound, but the reproducers calls connect only once per
>> socket. So there is no "connect to a new socket", no?
>> But w/e, see below.
>
> Yes, but it can be reproduced this way too. It can also happen with a
> close() on the remote peer 'o', and a send to 'o' from 's', which the
> reproducer can do as pointed out Michal. The patch I sent deals with
> both cases.
As Michal also pointed out, there's a unix_dgram_disconnected routine
being called in both cases and insofar "deregistering" anything beyond
what unix_dgram_disconnected (and - insofar I can tell this -
unix_release_sock) already do is actually required, this would be the
obvious place to add it. A good step on the way to that would be to
write (and post) some test code which actually reproduces the problem in
a predictable way.
next prev parent reply other threads:[~2015-10-01 10:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-13 19:53 List corruption on epoll_ctl(EPOLL_CTL_DEL) an AF_UNIX socket Mathias Krause
2015-09-14 2:39 ` Eric Wong
2015-09-29 18:09 ` Mathias Krause
2015-09-29 19:09 ` Jason Baron
2015-09-30 5:54 ` Mathias Krause
2015-09-30 7:34 ` Michal Kubecek
2015-10-01 2:55 ` Jason Baron
2015-09-30 10:56 ` Rainer Weikusat
2015-09-30 11:55 ` Mathias Krause
2015-09-30 13:25 ` Rainer Weikusat
2015-09-30 13:38 ` Mathias Krause
2015-09-30 13:51 ` Rainer Weikusat
2015-10-01 2:39 ` Jason Baron
2015-10-01 10:33 ` Rainer Weikusat [this message]
2015-10-01 12:10 ` Rainer Weikusat
2015-10-01 12:58 ` Rainer Weikusat
2015-09-15 17:07 ` Rainer Weikusat
2015-09-15 18:15 ` Mathias Krause
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=87oagiho88.fsf@doppelsaurus.mobileactivedefense.com \
--to=rweikusat@mobileactivedefense$(echo .)com \
--cc=dave@stgolabs$(echo .)net \
--cc=davem@davemloft$(echo .)net \
--cc=davidel@xmailserver$(echo .)org \
--cc=eric.dumazet@gmail$(echo .)com \
--cc=jbaron@akamai$(echo .)com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=minipli@googlemail$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=normalperson@yhbt$(echo .)net \
--cc=olivier@mauras$(echo .)ch \
--cc=pageexec@freemail$(echo .)hu \
--cc=peterz@infradead$(echo .)org \
--cc=torvalds@linux-foundation$(echo .)org \
--cc=viro@zeniv$(echo .)linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox