linux-kernel - Re: [PATCH] task_struct: Only use anon struct under randstruct plugin

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Message-ID: <CAGXu5j+an4OwLMCqGMqCN=dh1GH-_PQTDGFL_WhpbOSNXgYynA@mail.gmail.com>
Date:   Tue, 27 Mar 2018 17:30:47 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH] task_struct: Only use anon struct under randstruct plugin

On Tue, Mar 27, 2018 at 4:03 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Tue, 27 Mar 2018 14:36:09 -0700 Kees Cook <keescook@...omium.org> wrote:
>> Reported-by: Peter Zijlstra <peterz@...radead.org>
>> Fixes: 29e48ce87f1e ("task_struct: Allow randomized")
>> Cc: stable@...r.kernel.org
>
> Why cc:stable?

Since the padding existed in all configs, it's kind of an ugly wart
and should likely be fixed up for 4.14 and 4.15 -stable.

> So the mysterious 40 byte bloat is still present in this case?

Given how insane[1] task_struct can end up under randstruct, these 40
bytes aren't too bad. I've added fixing this to the randstruct to-do
list, but I don't view it as high priority.

-Kees
[1] https://git.kernel.org/linus/ffa47aa678cfaa9b88e8a26cfb115b4768325121

-- 
Kees Cook
Pixel Security