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

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Date:	Tue, 11 Nov 2014 11:52:27 +0100
From:	Richard Weinberger <richard@....at>
To:	David Miller <davem@...emloft.net>, luto@...capital.net
CC:	tglx@...utronix.de, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, linux-arch@...r.kernel.org,
	viro@...iv.linux.org.uk, richard.weinberger@...il.com,
	hpa@...or.com, mingo@...nel.org, keescook@...omium.org
Subject: Re: [PATCH v2] all arches, signal: Move restart_block to struct task_struct

Am 11.11.2014 um 03:13 schrieb David Miller:
> From: Andy Lutomirski <luto@...capital.net>
> Date: Mon, 10 Nov 2014 14:03:23 -0800
> 
>> 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?
> 
> No objections wrt. sparc and if things break I'll help fix it.

Same for UML.
Acked-by: Richard Weinberger <richard@....at>

Thanks,
//richard
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