4.9 - RHSA-2012:0676

Problem Description:

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

The Red Hat Security Response Team has rated this update as having moderate 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.

A flaw was found in the way the KVM_CREATE_IRQCHIP ioctl was handled. Calling this ioctl when at least one virtual CPU (VCPU) already existed could lead to a NULL pointer dereference later when the VCPU is scheduled to run. A malicious user in the kvm group on the host could use this flaw to crash the host. (CVE-2012-1601)

A flaw was found in the way device memory was handled during guest device removal. Upon successful device removal, memory used by the device was not properly unmapped from the corresponding IOMMU or properly released from the kernel, leading to a memory leak. A malicious user in the kvm group on the host who has the ability to assign a device to a guest could use this flaw to crash the host. (CVE-2012-2121)

This update also fixes the following bug:

* An off-by-one error in the QEMU guest's memory management could, in rare cases, cause QEMU-KVM to crash due to a segmentation fault in tb_invalidate_phys_page_range() if a device initiated DMA into a specific guest address. In a reported case, this issue presented on a system that had a guest using the 8139cp network driver. (BZ#816207)

All users of kvm are advised to upgrade to these updated packages, which contain backported patches to correct these issues. Note that 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/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.

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

808199 - CVE-2012-1601 kernel: kvm: irqchip_in_kernel() and vcpu->arch.apic inconsistency 814149 - CVE-2012-2121 kvm: device assignment page leak