Re: [PATCH v2] all arches, signal: Move restart_block to struct task_struct

[David Miller]

From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Date: Mon, 10 Nov 2014 14:03:23 -0800

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