oss-security - Re: Xen Security Advisory 98 - insufficient permissions checks accessing guest memory on ARM

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Date: Wed, 4 Jun 2014 17:05:01 +0100
From: Ian Jackson <Ian.Jackson@...citrix.com>
To: <cve-assign@...re.org>
CC: <security@....org>, <oss-security@...ts.openwall.com>
Subject: Re: Xen Security Advisory 98 - insufficient permissions checks accessing guest memory on ARM

cve-assign@...re.org writes ("Re: Xen Security Advisory 98 - insufficient permissions checks accessing guest memory on ARM"):
...
> > When accessing guest memory Xen does not correctly perform permissions
> > checks on the (possibly guest provided) virtual address ... This
> > allows a guest to write to memory which it should only be able to
> > read.
> 
> > In the event that a guest executes code from a page which has been
> > shared read-only with another guest it would be possible to mount a
> > take over attack on that guest.
> 
> Use CVE-2014-3969.

Thanks.  I have sent out updated versions of XSA-96 and -98.

> Our understanding is that "executes code from a page which has been
> shared read-only" depends on the permissions issue (lack of a check
> for execute permission), and is not an independent problem.

That is correct.

Thanks,
Ian.

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