Important: kvm security and bug fix update
Security Advisory: Important
Updated kvm packages that fix three security issues and multiple bugs are
now available for Red Hat Enterprise Linux 5.
The Red Hat Security Response Team has rated this update as having
important security impact. Common Vulnerability Scoring System (CVSS) base
scores, which give detailed severity ratings, are available for each
vulnerability from the CVE links in the References section.
KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for
the standard Red Hat Enterprise Linux kernel.
It was found that QEMU-KVM on the host did not validate all pointers
provided from a guest system's QXL graphics card driver. A privileged guest
user could use this flaw to cause the host to dereference an invalid
pointer, causing the guest to crash (denial of service) or, possibly,
resulting in the privileged guest user escalating their privileges on the
host. (CVE-2010-0431)
A flaw was found in QEMU-KVM, allowing the guest some control over the
index used to access the callback array during sub-page MMIO
initialization. A privileged guest user could use this flaw to crash the
guest (denial of service) or, possibly, escalate their privileges on the
host. (CVE-2010-2784)
A NULL pointer dereference flaw was found when the host system had a
processor with the Intel VT-x extension enabled. A privileged guest user
could use this flaw to trick the host into emulating a certain instruction,
which could crash the host (denial of service). (CVE-2010-0435)
This update also fixes the following bugs:
All KVM users should upgrade to these updated packages, which contain
backported patches to resolve these issues. Note: The procedure in the
Solution section must be performed before this update will take effect.
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.
This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259
The following procedure must be performed before this update will take
effect:
1) Stop all KVM guest virtual machines.
2) Either reboot the hypervisor machine or, as the root user, remove (using
"modprobe -r [module]") and reload (using "modprobe [module]") all of the
following modules which are currently running (determined using "lsmod"):
kvm, ksm, kvm-intel or kvm-amd.
3) Restart the KVM guest virtual machines.
Vulmon