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

[Kees Cook]

On Wed, Apr 13, 2016 at 7:11 AM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> On Wed, Apr 13, 2016 at 3:19 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>>
>> * Kees Cook <keescook@xxxxxxxxxxxx> 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