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From: Alexander Potapenko <glider@google.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>,
	Dmitriy Vyukov <dvyukov@google.com>,
	Kees Cook <keescook@chromium.org>,
	Laura Abbott <labbott@redhat.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH 1/3] mm: security: introduce the init_allocations=1 boot option
Date: Thu, 18 Apr 2019 18:43:27 +0200	[thread overview]
Message-ID: <CAG_fn=URD0WL+RE90ZE2FZM4=p2zE9V+YA2RW-LrWnuqYTwvKQ@mail.gmail.com> (raw)
In-Reply-To: <981d439a-1107-2730-f27e-17635ee4a125@intel.com>

On Thu, Apr 18, 2019 at 6:35 PM Dave Hansen <dave.hansen@intel.com> 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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  reply	other threads:[~2019-04-18 16:43 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-18 15:42 [PATCH 0/3] RFC: add init_allocations=1 boot option Alexander Potapenko
2019-04-18 15:42 ` Alexander Potapenko
2019-04-18 15:42 ` [PATCH 1/3] mm: security: introduce the " Alexander Potapenko
2019-04-18 15:42   ` Alexander Potapenko
2019-04-18 16:35   ` Dave Hansen
2019-04-18 16:43     ` Alexander Potapenko [this message]
2019-04-18 16:43       ` Alexander Potapenko
2019-04-18 16:50       ` Alexander Potapenko
2019-04-18 16:50         ` Alexander Potapenko
2019-04-23  8:31     ` Michal Hocko
2019-04-18 22:08   ` Randy Dunlap
2019-04-23 19:00   ` Kees Cook
2019-04-23 19:00     ` Kees Cook
2019-04-26 12:12     ` Alexander Potapenko
2019-04-26 12:12       ` Alexander Potapenko
2019-04-23 20:36   ` Dave Hansen
2019-04-26 14:14   ` Christopher Lameter
2019-04-26 14:14     ` Christopher Lameter
     [not found]   ` <alpine.DEB.2.21.1904260911570.8340@nuc-kabylake>
2019-04-26 15:24     ` Christopher Lameter
2019-04-26 15:24       ` Christopher Lameter
2019-04-26 15:48       ` Alexander Potapenko
2019-04-26 15:48         ` Alexander Potapenko
2019-04-18 15:42 ` [PATCH 2/3] gfp: mm: introduce __GFP_NOINIT Alexander Potapenko
2019-04-18 15:42   ` Alexander Potapenko
2019-04-18 16:52   ` Dave Hansen
2019-04-23 19:14     ` Kees Cook
2019-04-23 19:14       ` Kees Cook
2019-04-23 20:40       ` Dave Hansen
2019-04-23 19:11   ` Kees Cook
2019-04-23 19:11     ` Kees Cook
2019-04-18 15:42 ` [PATCH 3/3] RFC: net: apply __GFP_NOINIT to AF_UNIX sk_buff allocations Alexander Potapenko
2019-04-18 15:42   ` Alexander Potapenko
2019-04-23 19:17   ` Kees Cook
2019-04-23 19:17     ` Kees Cook
2019-04-18 15:44 ` [PATCH 0/3] RFC: add init_allocations=1 boot option Alexander Potapenko
2019-04-18 15:44   ` Alexander Potapenko
2019-04-18 22:07 ` Randy Dunlap
2019-04-23 18:49 ` Kees Cook
2019-04-23 18:49   ` Kees Cook
2019-04-26 12:39   ` Alexander Potapenko
2019-04-26 12:39     ` Alexander Potapenko

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