7.2 - RHSA-2014:0704

Problem Description:

Updated qemu-kvm packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 7.

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:

Red Hat Enterprise Linux Client (v. 7) - x86_64 Red Hat Enterprise Linux Client Optional (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64 Red Hat Enterprise Linux Server (v. 7) - x86_64 Red Hat Enterprise Linux Server Optional (v. 7) - x86_64 Red Hat Enterprise Linux Workstation (v. 7) - x86_64 Red Hat Enterprise Linux Workstation Optional (v. 7) - x86_64

3. Description:

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm packages provide a user-space component to run virtual machines using KVM.

An out-of-bounds memory access flaw was found in the way QEMU's IDE device driver handled the execution of SMART EXECUTE OFFLINE commands. A privileged guest user could use this flaw to corrupt QEMU process memory on the host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process. (CVE-2014-2894)

This update also fixes the following bugs:

* Prior to this update, a bug in the migration code caused the following error on specific machine types: after a Red Hat Enterprise Linux 6.5 guest was migrated from a Red Hat Enterprise Linux 6.5 host to a Red Hat Enterprise Linux 7.0 host and then restarted, the boot failed and the guest automatically restarted. Thus, the guest entered an endless loop. With this update, the migration code has been fixed and the Red Hat Enterprise Linux 6.5 guests migrated in the aforementioned scenario now boot properly. (BZ#1091322)

* Due to a regression bug in the iSCSI driver, the qemu-kvm process terminated unexpectedly with a segmentation fault when the "write same" command was executed in guest mode under the iSCSI protocol. This update fixes the regression and the "write same" command now functions in guest mode under iSCSI as intended. (BZ#1090978)

* Due to a mismatch in interrupt request (IRQ) routing, migration of a Red Hat Enterprise Linux 6.5 guest from a Red Hat Enterprise Linux 6.5 host to a Red Hat Enterprise Linux 7.0 host could produce a call trace. This happened if memory ballooning and a Universal Host Control Interface (UHCI) device were used at the same time on certain machine types. With this patch, the IRQ routing mismatch has been amended and the described migration now proceeds as expected. (BZ#1090981)

* Previously, an internal error prevented KVM from executing a CPU hot plug on a Red Hat Enterprise Linux 7 guest running on a Red Hat Enterprise Linux 7 host. This update addresses the internal error and CPU hot plugging in the described scenario now functions correctly. (BZ#1094820)

All qemu-kvm users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing this update, shut down all running virtual machines. Once all virtual machines have shut down, start them again for this update to 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/site/articles/11258

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

1087971 - CVE-2014-2894 QEMU: out of bounds buffer accesses, guest triggerable via IDE SMART 1090978 - qemu-kvm: iSCSI: Failure. SENSE KEY:ILLEGAL_REQUEST(5) ASCQ:INVALID_FIELD_IN_CDB(0x2400) 1090981 - Guest hits call trace migrate from RHEL6.5 to RHEL7.0 host with -M 6.1 & balloon & uhci device 1091322 - fail to reboot guest after migration from RHEL6.5 host to RHEL7.0 host 1094820 - Hot plug CPU not working with RHEL6 machine types running on RHEL7 host.