Red Hat 7 RHSA-2014:0704-01 Moderate: qemu-kvm Memory Access Flaw

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.