Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
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Date: Tue, 23 Apr 2019 12:17:33 -0700
From: Kees Cook <keescook@...omium.org>
To: Alexander Potapenko <glider@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Christoph Lameter <cl@...ux.com>, 
	Dmitry Vyukov <dvyukov@...gle.com>, Laura Abbott <labbott@...hat.com>, Linux-MM <linux-mm@...ck.org>, 
	linux-security-module <linux-security-module@...r.kernel.org>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 3/3] RFC: net: apply __GFP_NOINIT to AF_UNIX sk_buff allocations

On Thu, Apr 18, 2019 at 8:42 AM Alexander Potapenko <glider@...gle.com> wrote:
>
> Add sock_alloc_send_pskb_noinit(), which is similar to
> sock_alloc_send_pskb(), but allocates with __GFP_NOINIT.
> This helps reduce the slowdown on hackbench from 9% to 0.1%.

I would include a detailed justification about why this is safe to do.
I imagine (but haven't looked) that the skb is immediately written to
after allocation, so this is basically avoiding a "double init". Is
that correct?

-- 
Kees Cook

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