kvm: buffer overflow in handling of MSR_KVM_SYSTEM_TIME
CVE: CVE-2013-1796
Component: kernel
Severity: Important
Release date: 2013-03-20T00:00:00+00:00

The kvm_set_msr_common function in arch/x86/kvm/x86.c in the Linux kernel through 3.8.4 does not ensure a required time_page alignment during an MSR_KVM_SYSTEM_TIME operation, which allows guest OS users to cause a denial of service (buffer overflow and host OS memory corruption) or possibly have unspecified other impact via a crafted application.

Statement: This issue did not affect the versions of Linux kernel as shipped with Red Hat
Enterprise Linux 5 and Red Hat Enterprise MRG as they did not provide support
for the KVM subsystem.

Remediation:
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/knowledge/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.
This update also fixes several bugs. Documentation for these changes will
be available shortly from the Technical Notes document linked to in the
References section.

Users should upgrade to these updated packages, which contain backported
patches to correct these issues. The system must be rebooted for this
update to 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
https://access.redhat.com/knowledge/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.
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/site/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.
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/knowledge/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.
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/knowledge/articles/11258

To upgrade Hypervisors in Red Hat Enterprise Virtualization
environments using the disk image provided by this package, refer to:

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Hypervisor_Deployment_Guide/chap-Deployment_Guide-Upgrading_Red_Hat_Enterprise_Virtualization_Hypervisors.html