kernel-hardening - Re: [PATCH v2 00/29] implement KASLR for ARM

Follow @Openwall on Twitter for new release announcements and other news

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

Date: Wed, 6 Sep 2017 18:30:55 +0100
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: Tony Lindgren <tony@...mide.com>
Cc: "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>, Arnd Bergmann <arnd@...db.de>, 
	Nicolas Pitre <nico@...aro.org>, Russell King <linux@...linux.org.uk>, 
	Kees Cook <keescook@...omium.org>, Thomas Garnier <thgarnie@...gle.com>, 
	Marc Zyngier <marc.zyngier@....com>, Mark Rutland <mark.rutland@....com>, 
	Matt Fleming <matt@...eblueprint.co.uk>, Dave Martin <dave.martin@....com>
Subject: Re: [PATCH v2 00/29] implement KASLR for ARM

On 6 September 2017 at 18:12, Tony Lindgren <tony@...mide.com> wrote:
> * Ard Biesheuvel <ard.biesheuvel@...aro.org> [170906 09:36]:
>> Turns out I am calculating the top of DRAM incorrectly for boards
>> where less memory is present than the size of the lowmem region.
>>
>> Could you try this please? (Apologies for the whitespace)
>
> I think for 10 or so units per year you can actually buy
> a non-mangling outgoing SMTP service if nothing else helps..
>

Yeah, you're right, apologies. I use git-send-email mostly, but not
for inline snippets like this. And it is not actually the SMTP service
but the web client that mangles the whitespace

> Anyways, you patch manually applied fixed most of the random
> boot hangs for me, but I did see a new one after 11 boot
> attempts, see below.
>
> Regards,
>
> Tony
>
> 8< --------------
> Kernel image @ 0x81000000 [ 0x000000 - 0x426300 ]
> ## Flattened Device Tree blob at 84000000
>    Booting using the fdt blob at 0x84000000
>    Loading Device Tree to 86feb000, end 86fff2d5 ... OK
>
> Starting kernel ...
>
> regions.image_size:00e00000
> regions.pa_start:80000000
> regions.pa_end:87200000
> regions.zimage_start:81000000
> regions.zimage_size:00437320
> regions.dtb_start:86feb000
> regions.dtb_size:00012000
> regions.initrd_start:00000000
> regions.initrd_size:00000000
> num:00000028
> num:00000025
> *kaslr_offset:05e00000
> Uncompressing Linux... done, booting the kernel.
> Warning: Neither atags nor dtb found

OK, so in this case, 80000000 + 00e00000 + 05e00000 == 86c00000, which
is still below the DTB, but apparently, it has corrupted it anyway.

I will try to figure out what's going on here.

Thanks again for taking the time,
Ard.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.