linux-kernel - Re: [PATCH v4 00/20] x86, boot: kaslr cleanup and 64bit kaslr support

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Message-ID: <CAGXu5jJFcT9CgKvJSJ9rDOz4D8fJRhDbxBGwOpQhUA2OyYPAzg@mail.gmail.com>
Date:	Wed, 13 Apr 2016 23:02:38 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
	Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	Vivek Goyal <vgoyal@...hat.com>,
	Andy Lutomirski <luto@...nel.org>, lasse.collin@...aani.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Young <dyoung@...hat.com>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v4 00/20] x86, boot: kaslr cleanup and 64bit kaslr support

On Wed, Apr 13, 2016 at 7:11 AM, Kees Cook <keescook@...omium.org> wrote:
> On Wed, Apr 13, 2016 at 3:19 AM, Ingo Molnar <mingo@...nel.org> wrote:
>>
>> * Kees Cook <keescook@...omium.org> wrote:
>>
>>> FWIW, I've also had this tree up in my git branches, and the 0day
>>> tester hasn't complained at all about it in the last two weeks. I'd
>>> really like to see this in -next to fix the >4G (mainly kexec) issues
>>> and get us to feature parity with the arm64 kASLR work (randomized
>>> virtual address).

So, I've done this and suddenly realized I hadn't boot-tested i386. It
doesn't work, unfortunately. (Which I find strange: I'd expect 0day to
have noticed...)

Baoquan, have you tested this on 32-bit systems? I get a variety of
failures. Either it boots okay, it reboots, or I get tons of pte
errors like this:

[    0.000000] clearing pte for ram above max_low_pfn: pfn: 37dcc pmd:
f9144f7c pmd phys: 39144f7c pte: f9a1b730 pte phys: 39a1b730

Can you confirm? I suspect relocation problems, but ran out of time
today to debug it.

I have the entire series with cleaned up changelogs and various other
refactorings up here now:

http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/log/?h=kaslr/highmem

Thanks!

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security