From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752540AbbLMSyh (ORCPT ); Sun, 13 Dec 2015 13:54:37 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:42731 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752175AbbLMSyf (ORCPT ); Sun, 13 Dec 2015 13:54:35 -0500 Date: Sun, 13 Dec 2015 18:54:29 +0000 From: Luis Henriques To: Ben Hutchings Cc: Eric Dumazet , Steffen Klassert , "David S. Miller" , linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: Re: [PATCH 3.16.y-ckt 009/126] sit: fix sit0 percpu double allocations Message-ID: <20151213185429.GA31826@charon> References: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> <1449653896-5236-10-git-send-email-luis.henriques@canonical.com> <1449893906.3836.5.camel@decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1449893906.3836.5.camel@decadent.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 12, 2015 at 04:18:26AM +0000, Ben Hutchings wrote: > On Wed, 2015-12-09 at 09:36 +0000, Luis Henriques wrote: > > 3.16.7-ckt21 -stable review patch.  If anyone has any objections, > > please let me know. > > > > ------------------ > > > > From: Eric Dumazet > > > > commit 4ece9009774596ee3df0acba65a324b7ea79387c upstream. > > > > sit0 device allocates its percpu storage twice : > > - One time in ipip6_tunnel_init() > > - One time in ipip6_fb_tunnel_init() > > > > Thus we leak 48 bytes per possible cpu per network namespace > > dismantle. > > > > ipip6_fb_tunnel_init() can be much simpler and does not > > return an error, and should be called after register_netdev() > [...] > > Doesn't this introduce a race condition when sit is a module?  There > seems to be nothing to prevent access to the partially initialised > device after calling register_netdev(), if sit_init_net() is called > during module loading rather than during namespace creation. > This seems to be an upstream issue, not specific to the 3.16.y-ckt stable kernel. If that is the case, I guess I'll just keep this patch and later apply the fix. Or do you think this race is really likely to be a worst problem than then issue the patch is trying to fix? Cheers, -- Luís > Ben. > > -- > Ben Hutchings > Knowledge is power. France is bacon. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from youngberry.canonical.com ([91.189.89.112]:42731 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752175AbbLMSyf (ORCPT ); Sun, 13 Dec 2015 13:54:35 -0500 Date: Sun, 13 Dec 2015 18:54:29 +0000 From: Luis Henriques To: Ben Hutchings Cc: Eric Dumazet , Steffen Klassert , "David S. Miller" , linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: Re: [PATCH 3.16.y-ckt 009/126] sit: fix sit0 percpu double allocations Message-ID: <20151213185429.GA31826@charon> References: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> <1449653896-5236-10-git-send-email-luis.henriques@canonical.com> <1449893906.3836.5.camel@decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1449893906.3836.5.camel@decadent.org.uk> Sender: stable-owner@vger.kernel.org List-ID: On Sat, Dec 12, 2015 at 04:18:26AM +0000, Ben Hutchings wrote: > On Wed, 2015-12-09 at 09:36 +0000, Luis Henriques wrote: > > 3.16.7-ckt21 -stable review patch.��If anyone has any objections, > > please let me know. > > > > ------------------ > > > > From: Eric Dumazet > > > > commit 4ece9009774596ee3df0acba65a324b7ea79387c upstream. > > > > sit0 device allocates its percpu storage twice : > > - One time in ipip6_tunnel_init() > > - One time in ipip6_fb_tunnel_init() > > > > Thus we leak 48 bytes per possible cpu per network namespace > > dismantle. > > > > ipip6_fb_tunnel_init() can be much simpler and does not > > return an error, and should be called after register_netdev() > [...] > > Doesn't this introduce a race condition when sit is a module? �There > seems to be nothing to prevent access to the partially initialised > device after calling register_netdev(), if sit_init_net() is called > during module loading rather than during namespace creation. > This seems to be an upstream issue, not specific to the 3.16.y-ckt stable kernel. If that is the case, I guess I'll just keep this patch and later apply the fix. Or do you think this race is really likely to be a worst problem than then issue the patch is trying to fix? Cheers, -- Lu�s > Ben. > > -- > Ben Hutchings > Knowledge is power. France is bacon.