4 - RHSA-2012:0149

Problem Description:

Updated kvm packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link 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 the kvm_vm_ioctl_assign_device() function in the KVM subsystem of a Linux kernel did not check if the user requesting device assignment was privileged or not. A member of the kvm group on the host could assign unused PCI devices, or even devices that were in use and whose resources were not properly claimed by the respective drivers, which could result in the host crashing. (CVE-2011-4347)

Red Hat would like to thank Sasha Levin for reporting this issue.

These updated kvm packages include several bug fixes. Space precludes documenting all of these changes in this advisory. Users are directed to the Red Hat Enterprise Linux 5.8 Technical Notes, linked to in the References, for information on the most significant of these changes.

All KVM users should 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.

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 https://access.redhat.com/kb/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.

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

701616 - limitation on max number of assigned devices does not take effect if hot-plug pci devices 703335 - KVM guest clocks jump forward one hour on reboot 703446 - Failed to ping guest after MTU is changed 704081 - mouse responds very slowly with huge memory 725876 - RTC interrupt problems with RHEL5 qemu/kvm (0.10 based) on 2.6.38+ guest kernels. 753860 - Fix kvm userspace compilation on RHEL-5 to match the kernel changes 756084 - CVE-2011-4347 kernel: kvm: device assignment DoS