Vigil@nce - Xen: denial of service via writes to the PCI bus
August 2015 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker that have administrator privileges in a guest system
can trigger changes in some PCI configuration registers of Xen, in
order to trigger a denial of service against the host server.
Impacted products: XenServer, Debian, Fedora, openSUSE, SUSE Linux
Enterprise Desktop, SLES, Ubuntu, Xen
Severity: 2/4
Creation date: 03/06/2015
DESCRIPTION OF THE VULNERABILITY
The Xen product may be configured to attribute some PCI address
ranges to a guest system.
Writes to the PCI bus are normally filtered by Xen. However, there
is a way for the guest system to make Xen rewrite some PCI
configuration registers whith the values previously known by Xen.
This bus access may alter the device states and disturb the
interrupt handling layer of the DOM0 kernel, which would lead to
its halt.
An attacker that have administrator privileges in a guest system
can therefore trigger changes in some PCI configuration registers
of Xen, in order to trigger a denial of service against the host
server.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/Xen-denial-of-service-via-writes-to-the-PCI-bus-17051