linux-kernel - Re: [PATCH v21 12/12] x86: Zero-pad the VVAR page

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Date:	Sun, 2 Mar 2014 11:46:03 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Stefani Seibold <stefani@...bold.net>
Cc:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, ak@...ux.intel.com, aarcange@...hat.com,
	john.stultz@...aro.org, luto@...capital.net, xemul@...allels.com,
	gorcunov@...nvz.org, andriy.shevchenko@...ux.intel.com,
	Martin.Runge@...de-schwarz.com, Andreas.Brief@...de-schwarz.com
Subject: Re: [PATCH v21 12/12] x86: Zero-pad the VVAR page


* Stefani Seibold <stefani@...bold.net> wrote:

> By coincidence, the VVAR page is at the end of an ELF segment.  As a
> result, if it ends up being a partial page, the kernel loader will
> leave garbage behind at the end of the vvar page.  Zero-pad it to a
> full page to fix this issue.
> 
> This has probably been broken since the VVAR page was introduced.
> On QEMU, if you dump the run-time contents of the VVAR page, you can
> find entertaining strings from seabios left behind.
> 
> It's remotely possible that this is a security bug -- conceivably
> there's some BIOS out there that leaves something sensitive in the
> few K of memory that is exposed to userspace.
> 
> Signed-off-by: Andy Lutomirski <luto@...capital.net>
> Signed-off-by: Stefani Seibold <stefani@...bold.net>

That's not a valid signoff sequence - if the patch came from Andy then 
the patch needs to contain a From: Andy line as well. If Andy acked or 
reviewed the patch then please add an Acked-by or Reviewed-by line.

Thanks,

	Ingo
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