From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH] netfilter: nf_conntrack: reserve two bytes for nf_ct_ext->len (v3) Date: Sun, 30 Mar 2014 13:35:04 +0200 Message-ID: <20140330113504.GA5895@localhost> References: <20140328092449.GA20844@paralelels.com> <1396000472-6130-1-git-send-email-avagin@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, vvs@parallels.com, Patrick McHardy , Jozsef Kadlecsik , "David S. Miller" To: Andrey Vagin Return-path: Content-Disposition: inline In-Reply-To: <1396000472-6130-1-git-send-email-avagin@openvz.org> Sender: netfilter-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org On Fri, Mar 28, 2014 at 01:54:32PM +0400, 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 > nf_ct_ext_types[5]->len = 2 > nf_ct_ext_types[6]->len = 16 > nf_ct_ext_types[7]->len = 8 > > I have seen "len" up to 280 and my host has crashes w/o this patch. > > The right way to fix this problem is reducing the size of the ecache > extension (4) and Florian is going to do this, but these changes will > be quite large to be appropriate for a stable tree. > > v2: rearrange the extension so ECACHE comes last. This is required to > prevent overflow of nf_ct_ext->offset. > v3: The previous attempt of rearranging constants doesn't work here, > because extensions may be added in a random order. Applied, thanks.