From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644AbbJLNgX (ORCPT ); Mon, 12 Oct 2015 09:36:23 -0400 Received: from mail-pa0-f49.google.com ([209.85.220.49]:35381 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752066AbbJLNgV (ORCPT ); Mon, 12 Oct 2015 09:36:21 -0400 Message-ID: <1444656979.27760.161.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH v4 0/3] net: unix: fix use-after-free From: Eric Dumazet To: Rainer Weikusat Cc: David Miller , jbaron@akamai.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, minipli@googlemail.com, normalperson@yhbt.net, viro@zeniv.linux.org.uk, davidel@xmailserver.org, dave@stgolabs.net, olivier@mauras.ch, pageexec@freemail.hu, torvalds@linux-foundation.org, peterz@infradead.org, joe@perches.com Date: Mon, 12 Oct 2015 06:36:19 -0700 In-Reply-To: <87pp0ki6xh.fsf@doppelsaurus.mobileactivedefense.com> References: <20151011.045557.2164838188213641141.davem@davemloft.net> <87pp0ki6xh.fsf@doppelsaurus.mobileactivedefense.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2015-10-12 at 13:54 +0100, Rainer Weikusat wrote: > David Miller writes: > > From: Jason Baron > > Date: Fri, 9 Oct 2015 00:15:59 -0400 > > > >> These patches are against mainline, I can re-base to net-next, please > >> let me know. > >> > >> They have been tested against: https://lkml.org/lkml/2015/9/13/195, > >> which causes the use-after-free quite quickly and here: > >> https://lkml.org/lkml/2015/10/2/693. > > > > I'd like to understand how patches that don't even compile can be > > "tested"? > > > > net/unix/af_unix.c: In function ‘unix_dgram_writable’: > > net/unix/af_unix.c:2480:3: error: ‘other_full’ undeclared (first use in this function) > > net/unix/af_unix.c:2480:3: note: each undeclared identifier is reported only once for each function it appears in > > > > Could you explain how that works, I'm having a hard time understanding > > this? > > This is basicallly a workaround for the problem that it's not possible > to tell epoll to let go of a certain wait queue: Instead of registering > the peer_wait queue via sock_poll_wait, a wait_queue_t under control of > the af_unix.c code is linked onto it which relays a wake up on the > peer_wait queue to the 'ordinary' wait queue associated with the polled > socket via custom wake function. But (at least the code I looked it) it > enqueues a unix socket on connect which has certain side effects (in > particular, /dev/log will have a seriously large wait queue of entirely > uninterested peers) and in many cases, this is simply not necessary, as > the additional peer_wait event is only interesting in case a peer of a > fan-in socket (like /dev/log) happens to be waiting for writeabilty via > poll/ select/ epoll/ ... > > Since the wait queue handling code is now under control of the af_unix.c > code, it can remove itself from the peer_wait queue prior to dropping > its reference to a peer on disconnect or on detecting a dead peer in > unix_dgram_sendmsg. > -- Okay, but David was asking how the patch was supposed to be tested, and applied, if it does not compile. A patch is not only showing the idea, but must be ready for inclusion. Please ?