From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751891AbdGYKiu (ORCPT ); Tue, 25 Jul 2017 06:38:50 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:48216 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751483AbdGYKir (ORCPT ); Tue, 25 Jul 2017 06:38:47 -0400 Date: Tue, 25 Jul 2017 11:38:28 +0100 From: Russell King - ARM Linux To: Leonard Crestez Cc: Thomas Garnier , Thomas Gleixner , Catalin Marinas , Will Deacon , Dave Martin , Chris Metcalf , Pratyush Anand , linux-arm-kernel@lists.infradead.org, LKML , Kernel Hardening Subject: Re: [PATCH 1/3] arm/syscalls: Move address limit check in loop Message-ID: <20170725103828.GJ31807@n2100.armlinux.org.uk> References: <20170719175900.124074-1-thgarnie@google.com> <1500978481.30745.10.camel@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1500978481.30745.10.camel@nxp.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 25, 2017 at 01:28:01PM +0300, Leonard Crestez wrote: > On Mon, 2017-07-24 at 10:07 -0700, Thomas Garnier wrote: > > On Wed, Jul 19, 2017 at 10:58 AM, Thomas Garnier > > wrote: > > > > > > The work pending loop can call set_fs after addr_limit_user_check > > > removed the _TIF_FSCHECK flag. To prevent the infinite loop, move > > > the addr_limit_user_check call at the beginning of the loop. > > > > > > Fixes: 73ac5d6a2b6a ("arm/syscalls: Check address limit on user- > > > mode return") > > > Reported-by: Leonard Crestez > > > Signed-off-by: Thomas Garnier > > > Any comments on this patch set? > > Tested-by: Leonard Crestez > > This appears to fix the original issue of failing to boot from NFS when > there are lots of alignment faults. But this is a very basic test > relative to the reach of this change. > > However the original patch has been in linux-next for a while and > apparently nobody else noticed system calls randomly hanging on arm. > > I assume maintainers need to give their opinion. I've already stated my opinion, which is different from what Linus has requested of Thomas. IMHO, the current approach is going to keep on causing problems along the lines that I've already pointed out. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@armlinux.org.uk (Russell King - ARM Linux) Date: Tue, 25 Jul 2017 11:38:28 +0100 Subject: [PATCH 1/3] arm/syscalls: Move address limit check in loop In-Reply-To: <1500978481.30745.10.camel@nxp.com> References: <20170719175900.124074-1-thgarnie@google.com> <1500978481.30745.10.camel@nxp.com> Message-ID: <20170725103828.GJ31807@n2100.armlinux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Jul 25, 2017 at 01:28:01PM +0300, Leonard Crestez wrote: > On Mon, 2017-07-24 at 10:07 -0700, Thomas Garnier wrote: > > On Wed, Jul 19, 2017 at 10:58 AM, Thomas Garnier > > wrote: > > > > > > The work pending loop can call set_fs after addr_limit_user_check > > > removed the _TIF_FSCHECK flag. To prevent the infinite loop, move > > > the addr_limit_user_check call at the beginning of the loop. > > > > > > Fixes: 73ac5d6a2b6a ("arm/syscalls: Check address limit on user- > > > mode return") > > > Reported-by: Leonard Crestez > > > Signed-off-by: Thomas Garnier > > > Any comments on this patch set? > > Tested-by: Leonard Crestez > > This appears to fix the original issue of failing to boot from NFS when > there are lots of alignment faults. But this is a very basic test > relative to the reach of this change. > > However the original patch has been in linux-next for a while and > apparently nobody else noticed system calls randomly hanging on arm. > > I assume maintainers need to give their opinion. I've already stated my opinion, which is different from what Linus has requested of Thomas. IMHO, the current approach is going to keep on causing problems along the lines that I've already pointed out. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 25 Jul 2017 11:38:28 +0100 From: Russell King - ARM Linux Message-ID: <20170725103828.GJ31807@n2100.armlinux.org.uk> References: <20170719175900.124074-1-thgarnie@google.com> <1500978481.30745.10.camel@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1500978481.30745.10.camel@nxp.com> Sender: Russell King - ARM Linux Subject: [kernel-hardening] Re: [PATCH 1/3] arm/syscalls: Move address limit check in loop To: Leonard Crestez Cc: Thomas Garnier , Thomas Gleixner , Catalin Marinas , Will Deacon , Dave Martin , Chris Metcalf , Pratyush Anand , linux-arm-kernel@lists.infradead.org, LKML , Kernel Hardening List-ID: On Tue, Jul 25, 2017 at 01:28:01PM +0300, Leonard Crestez wrote: > On Mon, 2017-07-24 at 10:07 -0700, Thomas Garnier wrote: > > On Wed, Jul 19, 2017 at 10:58 AM, Thomas Garnier > > wrote: > > > > > > The work pending loop can call set_fs after addr_limit_user_check > > > removed the _TIF_FSCHECK flag. To prevent the infinite loop, move > > > the addr_limit_user_check call at the beginning of the loop. > > > > > > Fixes: 73ac5d6a2b6a ("arm/syscalls: Check address limit on user- > > > mode return") > > > Reported-by: Leonard Crestez > > > Signed-off-by: Thomas Garnier > > > Any comments on this patch set? > > Tested-by: Leonard Crestez > > This appears to fix the original issue of failing to boot from NFS when > there are lots of alignment faults. But this is a very basic test > relative to the reach of this change. > > However the original patch has been in linux-next for a while and > apparently nobody else noticed system calls randomly hanging on arm. > > I assume maintainers need to give their opinion. I've already stated my opinion, which is different from what Linus has requested of Thomas. IMHO, the current approach is going to keep on causing problems along the lines that I've already pointed out. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.