Groups > linux.kernel > #1620633

Re: KASLR causes intermittent boot failures on some systems

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	Re: KASLR causes intermittent boot failures on some systems
Date	2017-04-10 21:10 +0200
Message-ID	<tuMRj-4S4-11@gated-at.bofh.it> (permalink)
References	<ttDn3-8qV-13@gated-at.bofh.it> <ttJC9-4GN-3@gated-at.bofh.it> <tuJTu-2D4-73@gated-at.bofh.it> <tuM4W-4ll-15@gated-at.bofh.it> <tuMeB-4oO-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, Apr 10, 2017 at 11:22 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Kees Cook <keescook@chromium.org> writes:
>
>> On Mon, Apr 10, 2017 at 8:49 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
>>> Kees Cook <keescook@chromium.org> writes:
>>>
>>>> On Fri, Apr 7, 2017 at 7:41 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
>>>>> Hi,
>>>>>
>>>>> commit 021182e52fe01 ("x86/mm: Enable KASLR for physical mapping memory
>>>>> regions") causes some of my systems with persistent memory (whether real
>>>>> or emulated) to fail to boot with a couple of different crash
>>>>> signatures.  The first signature is a NMI watchdog lockup of all but 1
>>>>> cpu, which causes much difficulty in extracting useful information from
>>>>> the console.  The second variant is an invalid paging request, listed
>>>>> below.
>>>>
>>>> Just to rule out some of the stuff in the boot path, does booting with
>>>> "nokaslr" solve this? (i.e. I want to figure out if this is from some
>>>> of the rearrangements done that are exposed under that commit, or if
>>>> it is genuinely the randomization that is killing the systems...)
>>>
>>> Adding "nokaslr" to the boot line does indeed make the problem go away.
>>
>> Are you booting with a memmap= flag?
>
> From my first email:
>
> [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.11.0-rc5+
> root=/dev/mapper/rhel_intel--lizardhead--04-root ro memmap=192G!1024G
> crashkernel=auto rd.lvm.lv=rhel_intel-lizardhead-04/root
> rd.lvm.lv=rhel_intel-lizardhead-04/swap console=ttyS0,115200n81
> LANG=en_US.UTF-8
>
> Did you not receive the attachments?

I see it now, thanks!

The memmap parsing was added in -rc1 (f28442497b5ca), so I'd expect
that to be handled. Hmmm.

-Kees

-- 
Kees Cook
Pixel Security

Thread

Re: KASLR causes intermittent boot failures on some systems Jeff Moyer <jmoyer@redhat.com> - 2017-04-10 18:00 +0200
  Re: KASLR causes intermittent boot failures on some systems Kees Cook <keescook@chromium.org> - 2017-04-10 20:20 +0200
    Re: KASLR causes intermittent boot failures on some systems Jeff Moyer <jmoyer@redhat.com> - 2017-04-10 20:30 +0200
      Re: KASLR causes intermittent boot failures on some systems Kees Cook <keescook@chromium.org> - 2017-04-10 21:10 +0200
        Re: KASLR causes intermittent boot failures on some systems Jeff Moyer <jmoyer@redhat.com> - 2017-04-10 21:20 +0200

csiph-web