From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v4] netlink: Fix autobind race condition that leads to zero port ID Date: Sun, 20 Sep 2015 23:11:04 -0700 (PDT) Message-ID: <20150920.231104.525285577747035896.davem@davemloft.net> References: <20150918111650.GA7508@gondor.apana.org.au> <20150920.225521.1063980101511317898.davem@davemloft.net> <20150921060636.GA30807@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: tj@kernel.org, cwang@twopensource.com, tom@herbertland.com, kafai@fb.com, kernel-team@fb.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, torvalds@linux-foundation.org, jiri@resnulli.us, nicolas.dichtel@6wind.com, tgraf@suug.ch, sfeldma@gmail.com To: herbert@gondor.apana.org.au Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:48989 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756064AbbIUGLF (ORCPT ); Mon, 21 Sep 2015 02:11:05 -0400 In-Reply-To: <20150921060636.GA30807@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: From: Herbert Xu Date: Mon, 21 Sep 2015 14:06:36 +0800 > On Sun, Sep 20, 2015 at 10:55:21PM -0700, David Miller wrote: >> From: Herbert Xu >> Date: Fri, 18 Sep 2015 19:16:50 +0800 >> >> > The commit c0bb07df7d981e4091432754e30c9c720e2c0c78 ("netlink: >> > Reset portid after netlink_insert failure") introduced a race >> > condition where if two threads try to autobind the same socket >> > one of them may end up with a zero port ID. This led to kernel >> > deadlocks that were observed by multiple people. >> > >> > This patch reverts that commit and instead fixes it by introducing >> > a separte rhash_portid variable so that the real portid is only set >> > after the socket has been successfully hashed. >> > >> > Fixes: c0bb07df7d98 ("netlink: Reset portid after netlink_insert failure") >> > Reported-by: Tejun Heo >> > Reported-by: Linus Torvalds >> > Signed-off-by: Herbert Xu >> >> Applied and queued up for -stable, thanks Herbert. > > Sorry but Dave but there are still races with v4 as Tejun pointed > out. I'm still working on it and I could post them as incremental > patches if that's the easiest. Oops, sorry about that. Yeah at this point incremental patches work the best. Thanks.