linux-kernel - Re: [PATCH v2] all arches, signal: Move restart_block to struct task

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Message-ID: <CALCETrWtBCFXzwCAh8fpeFv-EvPxYW20oRmFk1iCYwUvpft=Rw@mail.gmail.com>
Date:	Mon, 10 Nov 2014 14:03:23 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Richard Weinberger <richard.weinberger@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2] all arches, signal: Move restart_block to struct task_struct

On Wed, Oct 29, 2014 at 11:12 AM, Thomas Gleixner <tglx@...utronix.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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