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

[Andy Lutomirski]

On Tue, Nov 11, 2014 at 2:52 AM, Richard Weinberger <richard@xxxxxx> wrote:
> Am 11.11.2014 um 03:13 schrieb 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.
>
> Same for UML.
> Acked-by: Richard Weinberger <richard@xxxxxx>

akpm, do you consider this appropriate for either 3.19 or 3.20?  If
so, can you add it to the appropriate part of -mm?

Thanks,
Andy
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