Arbitrary Code Execution

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm package provides the user-space component for running virtual machines using KVM. Multiple buffer overflow, input validation, and out-of-bounds write flaws were found in the way the virtio, virtio-net, virtio-scsi, and usb drivers of QEMU handled state loading after migration. A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process. (CVE-2013-4148, CVE-2013-4151, CVE-2013-4535, CVE-2013-4536, CVE-2013-4541, CVE-2013-4542, CVE-2013-6399, CVE-2014-0182, CVE-2014-3461) 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) The CVE-2013-4148, CVE-2013-4151, CVE-2013-4535, CVE-2013-4536, CVE-2013-4541, CVE-2013-4542, CVE-2013-6399, CVE-2014-0182, and CVE-2014-3461 issues were discovered by Michael S. Tsirkin of Red Hat, Anthony Liguori, and Michael Roth. This update also fixes the following bugs: * Previously, under certain circumstances, libvirt failed to start guests which used a non-zero PCI domain and SR-IOV Virtual Functions (VFs), and returned the following error message: Can’t assign device inside non-zero PCI segment as this KVM module doesn’t support it. This update fixes this issue and guests using the aforementioned configuration no longer fail to start. (BZ#1099941) * Due to an incorrect initialization of the cpus_sts bitmap, which holds the enablement status of a vCPU, libvirt could fail to start a guest with an unusual vCPU topology (for example, a guest with three cores and two sockets). With this update, the initialization of cpus_sts has been corrected, and libvirt no longer fails to start the aforementioned guests. (BZ#1100575) 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.