[Xen-announce] Xen Security Advisory 94 - ARM hypervisor crash on guest interrupt controller access

[Xen.org security team <security@xxxxxxx>]

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                    Xen Security Advisory XSA-94

      ARM hypervisor crash on guest interrupt controller access

ISSUE DESCRIPTION
=================

When handling a guest access to the virtual GIC distributor (interrupt
controller) Xen could dereference a pointer before checking it for
validity leading to a hypervisor crash and host Denial of Service.

IMPACT
======

A buggy or malicious guest can crash the host.

VULNERABLE SYSTEMS
==================

Both 32- and 64-bit ARM systems are vulnerable from Xen 4.4 onward.

x86 systems are not vulnerable.

MITIGATION
==========

None.

NOTE REGARDING LACK OF EMBARGO
==============================

This bug was publicly reported on xen-devel, before it was appreciated
that there was a security problem.

CREDITS
=======

The initial bug was discovered by Thomas Leonard and the security
aspect was diagnosed by Julien Grall.

RESOLUTION
==========

Applying the appropriate attached patch resolves this issue.

xsa94.patch        xen-unstable, Xen 4.4.x

$ sha256sum xsa94*.patch
ad0f20577400756a1786daeafef86fa870727ec35b48f71f565e4a30dcbda58d  xsa94.patch
$
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Attachment: xsa94.patch
Description: Binary data

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