linux-kernel - Re: [edk2] Corrupted EFI region

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]

Date:	Wed, 7 Aug 2013 21:19:08 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Andrew Fish <afish@...le.com>
Cc:	edk2-devel@...ts.sourceforge.net, Laszlo Ersek <lersek@...hat.com>,
	linux-efi@...r.kernel.org, Gleb Natapov <gleb@...hat.com>,
	lkml <linux-kernel@...r.kernel.org>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [edk2] Corrupted EFI region

[ Readding Matthew Garrett to the Cc list, seeing as we both got removed
  for some unknown reason ]

On Wed, 07 Aug, at 10:23:56AM, Andrew Fish wrote:

> OK so I think I need some Cliff Notes here to help me understand what
> is going on...
> 
> type 4 is EfiBootServicesData and attr 0x0f is cache attributes with
> no request for a runtime mapping. This is not runtime memory so to the
> OS loader it is just memory EFI has used that will get freed back to
> the OS after ExitBootServices(), along with EfiBootServicesCode,
> EfiLoaderCode, and EfiLoaderData. The EfiLoaderCode and EfiLoaderData
> also get freed back to the OS and they just exist for the convenience
> of the OS loader. 
> 
> So I can't figure out why this maters? Given:

We've seen a bunch of systems that make calls into EfiBootServicesCode
after ExitBootServices(). There were some Apple machines in that list,
though I don't have the details but Matthew should.
 
So we map these regions unconditionally and in their original state,
otherwise the firmware will generate fatal page faults when trying to
access those memory regions.

-- 
Matt Fleming, Intel Open Source Technology Center
--
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/