2.1 - RHSA-2017:0083

Problem Description:

An update for qemu-kvm is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Low. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Client (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64 Red Hat Enterprise Linux Server (v. 7) - ppc64, ppc64le, x86_64 Red Hat Enterprise Linux Workstation (v. 7) - x86_64

3. Description:

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

Security Fix(es):

* An out-of-bounds read-access flaw was found in the QEMU emulator built with IP checksum routines. The flaw could occur when computing a TCP/UDP packet's checksum, because a QEMU function used the packet's payload length without checking against the data buffer's size. A user inside a guest could use this flaw to crash the QEMU process (denial of service). (CVE-2016-2857)

Red Hat would like to thank Ling Liu (Qihoo 360 Inc.) for reporting this issue.

Bug Fix(es):

* Previously, rebooting a guest virtual machine more than 128 times in a short period of time caused the guest to shut down instead of rebooting, because the virtqueue was not cleaned properly. This update ensures that the virtqueue is cleaned more reliably, which prevents the described problem from occurring. (BZ#1393484)

4. Solution:

For details on how to apply this update, which includes the changes described in this advisory, refer to:

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

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.

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

1296567 - CVE-2016-2857 Qemu: net: out of bounds read in net_checksum_calculate()