FreeBSD : xen-kernel -- x86 shadow pagetables: address width overflow (d51ced72-4212-11e6-942d-bc5ff45d0f28)

This script is Copyright (C) 2016 Tenable Network Security, Inc.


Synopsis :

The remote FreeBSD host is missing a security-related update.

Description :

The Xen Project reports :

In the x86 shadow pagetable code, the guest frame number of a
superpage mapping is stored in a 32-bit field. If a shadowed guest can
cause a superpage mapping of a guest-physical address at or above 2^44
to be shadowed, the top bits of the address will be lost, causing an
assertion failure or NULL dereference later on, in code that removes
the shadow.

A HVM guest using shadow pagetables can cause the host to crash.

A PV guest using shadow pagetables (i.e. being migrated) with PV
superpages enabled (which is not the default) can crash the host, or
corrupt hypervisor memory, and so a privilege escalation cannot be
ruled out.

See also :

http://xenbits.xen.org/xsa/advisory-173.html
http://www.nessus.org/u?3eaebead

Solution :

Update the affected package.

Risk factor :

High / CVSS Base Score : 7.2
(CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C)

Family: FreeBSD Local Security Checks

Nessus Plugin ID: 91934 ()

Bugtraq ID:

CVE ID: CVE-2016-3960

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