7.2 - RHSA-2015:1507

Problem Description:

Updated qemu-kvm packages that fix two security issues and one bug are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Important 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:

Red Hat Enterprise Linux Client (v. 7) - x86_64 Red Hat Enterprise Linux Client Optional (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64 Red Hat Enterprise Linux Server (v. 7) - ppc64, x86_64 Red Hat Enterprise Linux Server Optional (v. 7) - ppc64, 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 package provides the user-space component for running virtual machines using KVM.

A heap buffer overflow flaw was found in the way QEMU's IDE subsystem handled I/O buffer access while processing certain ATAPI commands. A privileged guest user in a guest with the CDROM drive enabled could potentially use this flaw to execute arbitrary code on the host with the privileges of the host's QEMU process corresponding to the guest. (CVE-2015-5154)

An out-of-bounds memory access flaw, leading to memory corruption or possibly an information leak, was found in QEMU's pit_ioport_read() function. A privileged guest user in a QEMU guest, which had QEMU PIT emulation enabled, could potentially, in rare cases, use this flaw to execute arbitrary code on the host with the privileges of the hosting QEMU process. (CVE-2015-3214)

Red Hat would like to thank Matt Tait of Google's Project Zero security team for reporting the CVE-2015-3214 issue. The CVE-2015-5154 issue was discovered by Kevin Wolf of Red Hat.

This update also fixes the following bug:

* Due to an incorrect implementation of portable memory barriers, the QEMU emulator in some cases terminated unexpectedly when a virtual disk was under heavy I/O load. This update fixes the implementation in order to achieve correct synchronization between QEMU's threads. As a result, the described crash no longer occurs. (BZ#1233643)

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.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

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

1229640 - CVE-2015-3214 qemu/kvm: i8254: out-of-bounds memory access in pit_ioport_read function 1243563 - CVE-2015-5154 qemu: ide: atapi: heap overflow during I/O buffer memory access