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Date: Tue, 30 May 2017 09:02:13 -0400
From: Daniel Micay <danielmicay@...il.com>
To: Florian Weimer <fweimer@...hat.com>, oss-security@...ts.openwall.com
Cc: Roee Hay <roeehay@...il.com>
Subject: Re: Linux kernel: stack buffer overflow with
 controlled payload in get_options() function

On Tue, 2017-05-30 at 14:52 +0200, Florian Weimer wrote:
> On 05/30/2017 01:51 PM, Daniel Micay wrote:
> > It's unreasonable to consider the kernel line untrusted. A CVE being
> > issued for one of these issues didn't make sense.
> 
> It's a potential Secure Boot bypass, so it matters in some theoretical
> sense to some downstreams which carry those Secure Boot patches.
> 
> (Although I have yet to see anyone to revoke a signature on a kernel
> with known root-to-ring-0 escalations, so the practical impact isn't
> large because an attack could still downgrade to a kernel with an
> exploitable vulnerability.)
> 
> Florian

How is it a secure boot bypass? If the secure boot implementation
doesn't cover the kernel line it's already broken.

The provided example was treated as a verified boot vulnerability by
Google and fixed. It isn't supposed to be possible to set the kernel
line with a locked bootloader on Nexus/Pixel devices. It was a bug.

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