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In-Reply-To: <alpine.DEB.2.11.1410291908290.5308@nanos>
References: <43c88012a4959cd427ab634906e697fbc524e847.1414604015.git.luto@amacapital.net>
 <alpine.DEB.2.11.1410291908290.5308@nanos>
From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 10 Nov 2014 14:03:23 -0800
Message-ID: <CALCETrWtBCFXzwCAh8fpeFv-EvPxYW20oRmFk1iCYwUvpft=Rw@mail.gmail.com>
Subject: Re: [PATCH v2] all arches, signal: Move restart_block to struct task_struct
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Richard Weinberger <richard.weinberger@gmail.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
        Kees Cook <keescook@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Wed, Oct 29, 2014 at 11:12 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, 29 Oct 2014, Andy Lutomirski wrote:
>
>> If an attacker can cause a controlled kernel stack overflow,
>> overwriting the restart block is a very juicy exploit target.
>> Moving the restart block to struct task_struct prevents this
>> exploit.
>>
>> Note that there are other fields in thread_info that are also easy
>> targets, at least on some architectures.
>>
>> It's also a decent simplification, since the restart code is more or
>> less identical on all architectures.
>
> I think that's the most important change. Moving common stuff into
> common code. The side effect of slightly reducing the attack surface
> is nice, but as Al pointed out not really the big win here.

Having gotten exactly zero feedback from any arch maintainer outside
of x86, am I supposed to pester people further?

--Andy

>
> Thanks,
>
>         tglx


-- 
Andy Lutomirski
AMA Capital Management, LLC
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