From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: Re: [PATCH v4] netlink: Fix autobind race condition that leads to zero port ID Date: Mon, 21 Sep 2015 14:06:36 +0800 Message-ID: <20150921060636.GA30807@gondor.apana.org.au> References: <20150917113034.GA14471@htj.duckdns.org> <20150918063609.GA31747@gondor.apana.org.au> <20150918111650.GA7508@gondor.apana.org.au> <20150920.225521.1063980101511317898.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: David Miller Return-path: Content-Disposition: inline In-Reply-To: <20150920.225521.1063980101511317898.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt