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Message-ID: <CAGXu5j+hm8whuGxJ9PBEdxrSwpdH9a-S5-7ReVmb+COyRo9=uw@mail.gmail.com>
Date: Thu, 3 Oct 2013 15:43:11 -0700
From: Kees Cook <keescook@...omium.org>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: LKML <linux-kernel@...r.kernel.org>, "x86@...nel.org" <x86@...nel.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Aaron Durbin <adurbin@...gle.com>,
Eric Northup <digitaleric@...gle.com>, Julien Tinnes <jln@...gle.com>, Will Drewry <wad@...gle.com>,
Mathias Krause <minipli@...glemail.com>, Zhang Yanfei <zhangyanfei@...fujitsu.com>
Subject: Re: [PATCH 3/7] x86, kaslr: find minimum safe relocation position
On Thu, Oct 3, 2013 at 3:23 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 10/03/2013 01:53 PM, Kees Cook wrote:
>> Examine all the known unsafe areas and avoid them by just raising the
>> minimum relocation position to be past them.
>>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>
>> + /* Minimum location must be above all these regions: */
>
> This is highly problematic. The standard protocol is to hoist the
> initramfs as high as possible in memory, so this may really unacceptably
> restrict the available range.
Doesn't this depend on the boot loader's behavior?
> It would be better to treat these the same as reserved regions in the
> e820 map as far as the address space picking algorithm is concerned.
Could this be considered a future optimization, or do you feel this is
required even for this first patch series landing?
-Kees
--
Kees Cook
Chrome OS Security
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