(RHSA-2008:0194) Important: xen security and bug fix update

The xen packages contain tools for managing the virtual machine monitor in
Red Hat Virtualization.

These updated packages fix the following security issues:

Daniel P. Berrange discovered that the hypervisor’s para-virtualized
framebuffer (PVFB) backend failed to validate the format of messages
serving to update the contents of the framebuffer. This could allow a
malicious user to cause a denial of service, or compromise the privileged
domain (Dom0). (CVE-2008-1944)

Markus Armbruster discovered that the hypervisor’s para-virtualized
framebuffer (PVFB) backend failed to validate the frontend’s framebuffer
description. This could allow a malicious user to cause a denial of
service, or to use a specially crafted frontend to compromise the
privileged domain (Dom0). (CVE-2008-1943)

Chris Wright discovered a security vulnerability in the QEMU block format
auto-detection, when running fully-virtualized guests. Such
fully-virtualized guests, with a raw formatted disk image, were able
to write a header to that disk image describing another format. This could
allow such guests to read arbitrary files in their hypervisor’s host.
(CVE-2008-2004)

Ian Jackson discovered a security vulnerability in the QEMU block device
drivers backend. A guest operating system could issue a block device
request and read or write arbitrary memory locations, which could lead to
privilege escalation. (CVE-2008-0928)

Tavis Ormandy found that QEMU did not perform adequate sanity-checking of
data received via the “net socket listen” option. A malicious local
administrator of a guest domain could trigger this flaw to potentially
execute arbitrary code outside of the domain. (CVE-2007-5730)

Steve Kemp discovered that the xenbaked daemon and the XenMon utility
communicated via an insecure temporary file. A malicious local
administrator of a guest domain could perform a symbolic link attack,
causing arbitrary files to be truncated. (CVE-2007-3919)

As well, in the previous xen packages, it was possible for Dom0 to fail to
flush data from a fully-virtualized guest to disk, even if the guest
explicitly requested the flush. This could cause data integrity problems on
the guest. In these updated packages, Dom0 always respects the request to
flush to disk.

Users of xen are advised to upgrade to these updated packages, which
resolve these issues.