From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH] netfilter: Force fake conntrack entry to be at least 8 bytes aligned Date: Mon, 13 Mar 2017 13:33:32 +0100 Message-ID: <20170313123332.GA6790@salvia> References: <20170311002526.1d21e750@gandalf.local.home> <20170311091222.GA24201@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Steven Rostedt (VMware)" , LKML , netdev , David Miller , Jozsef Kadlecsik , coreteam@netfilter.org, netfilter-devel@vger.kernel.org To: Florian Westphal Return-path: Content-Disposition: inline In-Reply-To: <20170311091222.GA24201@breakpoint.cc> Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org On Sat, Mar 11, 2017 at 10:12:22AM +0100, Florian Westphal wrote: > Steven Rostedt (VMware) wrote: > > Since the nfct and nfctinfo have been combined, the nf_conn structure > > must be at least 8 bytes aligned, as the 3 LSB bits are used for the > > nfctinfo. But there's a fake nf_conn structure to denote untracked > > connections, which is created by a PER_CPU construct. This does not > > guarantee that it will be 8 bytes aligned and can break the logic in > > determining the correct nfctinfo. > > > > I triggered this on a 32bit machine with the following error: > [..] > > Ugh. Originally I had planned to also submit followup changes > to get rid of the untracked objects but that part got delayed. > > > By using DEFINE/DECLARE_PER_CPU_ALIGNED we can enforce at least 8 byte > > alignment as all cache line sizes are at least 8 bytes or more. > > Thanks for fixing this! > > Acked-by: Florian Westphal Applied, thanks.