From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH] netfilter: nf_conntrack: reserve two bytes for nf_ct_ext->len Date: Thu, 27 Mar 2014 16:01:01 +0000 Message-ID: <20140327160100.GA32534@macbook.localnet> References: <1395934354-13226-1-git-send-email-avagin@openvz.org> <20140327155033.GF21741@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrey Vagin , linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, vvs@parallels.com, Pablo Neira Ayuso , Jozsef Kadlecsik , "David S. Miller" To: Florian Westphal Return-path: Content-Disposition: inline In-Reply-To: <20140327155033.GF21741@breakpoint.cc> Sender: linux-kernel-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org On Thu, Mar 27, 2014 at 04:50:33PM +0100, Florian Westphal wrote: > Andrey Vagin wrote: > > "len" contains sizeof(nf_ct_ext) and size of extensions. In a worst > > case it can contain all extensions. Bellow you can find sizes for all > > types of extensions. Their sum is definitely bigger than 256. > > > > nf_ct_ext_types[0]->len = 24 > > nf_ct_ext_types[1]->len = 32 > > nf_ct_ext_types[2]->len = 24 > > nf_ct_ext_types[3]->len = 32 > > nf_ct_ext_types[4]->len = 152 > > Guess its the timer in the ecache extension (with LOCKDEP on probably). > > I'll submit a patch to get rid of that shortly. > > I think your patch is fine because the 'no timer > in ecache extension' change is quite large, needs review/stress testing > etc and is inapropriate for stable tree anyway. > > > I have seen "len" up to 280 and my host has crashes w/o this patch. > > ecache is 24 bytes without that timer, should be < 256 in total for > all extensions. > > I think BUILD_BUG_ON test would be nice. We also have variable length extensions, but we definitely should catch this *somewhere*.