RHSA-2009:1465 - Security Advisory

Topic

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

This update has been rated as having important security impact by the Red
Hat Security Response Team.

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.

The kvm_emulate_hypercall() implementation was missing a check for the
Current Privilege Level (CPL). A local, unprivileged user in a virtual
machine could use this flaw to cause a local denial of service or escalate
their privileges within that virtual machine. (CVE-2009-3290)

This update also fixes the following bugs:

• non-maskable interrupts (NMI) were not supported on systems with AMD

processors. As a consequence, Windows Server 2008 R2 guests running with
more than one virtual CPU assigned on systems with AMD processors would
hang at the Windows shut down screen when a restart was attempted. This
update adds support for NMI filtering on systems with AMD processors,
allowing clean restarts of Windows Server 2008 R2 guests running with
multiple virtual CPUs. (BZ#520694)

• significant performance issues for guests running 64-bit editions of

Windows. This update improves performance for guests running 64-bit
editions of Windows. (BZ#521793)

• Windows guests may have experienced time drift. (BZ#521794)
• removing the Red Hat VirtIO Ethernet Adapter from a guest running Windows

Server 2008 R2 caused KVM to crash. With this update, device removal should
not cause this issue. (BZ#524557)

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 takes effect.

Solution

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

This update is available via 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 takes 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.

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.4 x86_64
• Red Hat Enterprise Linux Workstation 5 x86_64

Fixes

• BZ - 520694 - NMI filtering for AMD (Windows 2008 R2 KVM guest can not restart when set it as multiple cpus)
• BZ - 521793 - windows 64 bit does vmexit on each cr8 access.
• BZ - 521794 - rtc-td-hack stopped working. Time drifts in windows
• BZ - 524124 - CVE-2009-3290 kernel: KVM: x86: Disallow hypercalls for guest callers in rings > 0
• BZ - 524557 - QEMU crash (during virtio-net WHQL tests for Win2008 R2)

CVEs

• CVE-2009-3290

References

• http://www.redhat.com/security/updates/classification/#important