linux-kernel - Re: PROBLEM: [Launchpad #1396889] [Lenovo ThinkPad T400] kexec reboot fails

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGXu5jJYw+x=YU5O1k=isuxx6gKRP4zQYj03tZYx6mLW0qLPfw@mail.gmail.com>
Date:	Mon, 1 Dec 2014 14:59:38 -0800
From:	Kees Cook <keescook@...omium.org>
To:	MegaBrutal <megabrutal@...il.com>
Cc:	Linux kernel <linux-kernel@...r.kernel.org>,
	Baoquan He <bhe@...hat.com>, "x86@...nel.org" <x86@...nel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: PROBLEM: [Launchpad #1396889] [Lenovo ThinkPad T400] kexec reboot fails

On Mon, Dec 1, 2014 at 2:45 PM, MegaBrutal <megabrutal@...il.com> wrote:
> 2014-12-01 7:32 GMT+01:00 MegaBrutal <megabrutal@...il.com>:
>> [X.] Other notes, patches, fixes, workarounds:
>> Downstream report (Ubuntu Launchpad):
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1396889
>>
>> With kernel bisection, I've found, the first bad commit is
>> 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc x86, kaslr: Return location
>> from decompress_kernel
>> which introduces KASLR.
>> http://lkml.kernel.org/r/1381450698-28710-3-git-send-email-keescook@chromium.org
>>
>> The problem only presents itself when CONFIG_RANDOMIZE_BASE=y.
>>
>> For workaround, there is a "nokaslr" kernel parameter to disable the
>> feature, even if the kernel was compiled with CONFIG_RANDOMIZE_BASE.
>
> Need to add: as I tested today, unfortunately the "nokaslr" kernel
> option doesn't work around the bug. If a kernel was compiled with
> CONFIG_RANDOMIZE_BASE, it won't properly kexec on my ThinkPad T400,
> even if the "nokaslr" kernel option is provided!
>
> This could actually help to find the bug, as whatever bad happens must
> happen before the kernel checks for the presence of the "nokaslr"
> kernel parameter.

I suspect you're encountering a subset of the same problems as
described in this thread:
https://lkml.org/lkml/2014/9/30/90

If you can test those patches, that may help demonstrate their utility.

Thanks!

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/