Xen.org security team
2012-Sep-05 11:14 UTC
Xen Security Advisory 18 (CVE-2012-3516) - grant table entry swaps have inadequate bounds checking
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Xen Security Advisory CVE-2012-3516 / XSA-18
version 2
grant table entry swaps have inadequate bounds checking
UPDATES IN VERSION 2
===================
Public release.
ISSUE DESCRIPTION
================
The grant table hypercall''s GNTTABOP_swap_grant_ref sub-operation does
not perform adequate checks on the input grant references.
IMPACT
=====
A malicious guest kernel or administrator can crash the host.
It may be possible for an attacker to swap a valid grant reference,
which they control, with an invalid one allowing them to write
abitrary values to hypervisor memory. This could potentially lead to a
privilege escalation.
VULNERABLE SYSTEMS
=================
Xen-unstable, including Xen 4.2 release candidates are vulnerable to
this issue.
Xen 4.1 and earlier do not include this hypercall and are therefore
not vulnerable.
MITIGATION
=========
The only mitigation is not to run guests which have untrusted
administrators.
RESOLUTION
=========
Applying the attached patch will resolve the issue.
PATCH INFORMATION
================
The attached patch resolves this issue
Xen unstable xsa18-unstable.patch
$ sha256sum xsa18-unstable.patch
ad354a1964fc52b0e48d405514156935cc8dfcb5bdaee307e3e74afcc0ca8914
xsa18-unstable.patch
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