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Date: Thu, 18 Apr 2019 18:43:27 +0200
From: Alexander Potapenko <>
To: Dave Hansen <>
Cc: Andrew Morton <>, Christoph Lameter <>, 
	Dmitriy Vyukov <>, Kees Cook <>, 
	Laura Abbott <>, Linux Memory Management List <>, 
	linux-security-module <>, 
	Kernel Hardening <>
Subject: Re: [PATCH 1/3] mm: security: introduce the init_allocations=1 boot option

On Thu, Apr 18, 2019 at 6:35 PM Dave Hansen <> wrote:
> On 4/18/19 8:42 AM, Alexander Potapenko wrote:
> > This option adds the possibility to initialize newly allocated pages and
> > heap objects with zeroes. This is needed to prevent possible information
> > leaks and make the control-flow bugs that depend on uninitialized values
> > more deterministic.
> Isn't it better to do this at free time rather than allocation time?  If
> doing it at free, you can't even have information leaks for pages that
> are in the allocator.
I should have mentioned this in the patch description, as this
question is being asked every time I send a patch :)
If we want to avoid double initialization and take advantage of
__GFP_NOINIT (see the second and third patches in the series) we need
to do initialize the memory at allocation time, because free() and
free_pages() don't accept GFP flags.

Alexander Potapenko
Software Engineer

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