linux-kernel - Re: [PATCH 1/3] arm/syscalls: Move address limit check in loop

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Date:   Tue, 25 Jul 2017 13:28:01 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Thomas Garnier <thgarnie@...gle.com>,
        Russell King <linux@...linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Catalin Marinas" <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "Dave Martin" <Dave.Martin@....com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Pratyush Anand <panand@...hat.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 1/3] arm/syscalls: Move address limit check in loop

On Mon, 2017-07-24 at 10:07 -0700, Thomas Garnier wrote:
> On Wed, Jul 19, 2017 at 10:58 AM, Thomas Garnier <thgarnie@...gle.com
> > 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 <leonard.crestez@....com>
> > Signed-off-by: Thomas Garnier <thgarnie@...gle.com>

> Any comments on this patch set?

Tested-by: Leonard Crestez <leonard.crestez@....com>

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.