4.9 - RHSA-2015:0869

Problem Description:

Updated kvm packages that fix two security issues are now available for Red Hat Enterprise Linux 5.

Red Hat Product Security 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.

2. Relevant releases/architectures:

RHEL Desktop Multi OS (v. 5 client) - x86_64 RHEL Virtualization (v. 5 server) - x86_64

3. Description:

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 KVM's Write to Model Specific Register (WRMSR) instruction emulation would write non-canonical values passed in by the guest to certain MSRs in the host's context. A privileged guest user could use this flaw to crash the host. (CVE-2014-3610)

A race condition flaw was found in the way the Linux kernel's KVM subsystem handled PIT (Programmable Interval Timer) emulation. A guest user who has access to the PIT I/O ports could use this flaw to crash the host. (CVE-2014-3611)

Red Hat would like to thank Lars Bull of Google and Nadav Amit for reporting the CVE-2014-3610 issue, and Lars Bull of Google for reporting the CVE-2014-3611 issue.

All kvm users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. Note: The procedure in the Solution section must be performed before this update will take effect.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

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.

5. Bugs fixed (https://bugzilla.redhat.com/):

1144878 - CVE-2014-3611 kernel: kvm: PIT timer race condition 1144883 - CVE-2014-3610 kernel: kvm: noncanonical MSR writes