[USN-2979-2] Linux kernel (Xenial HWE) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-2979-2
May 16, 2016

linux-lts-xenial vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the kernel.

Software Description:
- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

Details:

USN-2979-1 fixed vulnerabilities in the Linux kernel for Ubuntu 16.04
LTS. This update provides the corresponding updates for the Linux
Hardware Enablement (HWE) kernel from Ubuntu 16.04 LTS for Ubuntu
14.04 LTS.

David Matlack discovered that the Kernel-based Virtual Machine (KVM)
implementation in the Linux kernel did not properly restrict variable
Memory Type Range Registers (MTRR) in KVM guests. A privileged user in a
guest VM could use this to cause a denial of service (system crash) in the
host, expose sensitive information from the host, or possibly gain
administrative privileges in the host. (CVE-2016-3713)

Philip Pettersson discovered that the Linux kernel's ASN.1 DER decoder did
not properly process certificate files with tags of indefinite length. A
local unprivileged attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code with administrative
privileges. (CVE-2016-0758)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 14.04 LTS:
  linux-image-4.4.0-22-generic    4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-generic-lpae  4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-lowlatency  4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-powerpc-e500mc  4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-powerpc-smp  4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-powerpc64-emb  4.4.0-22.40~14.04.1
  linux-image-4.4.0-22-powerpc64-smp  4.4.0-22.40~14.04.1

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-xenial, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  http://www.ubuntu.com/usn/usn-2979-2
  http://www.ubuntu.com/usn/usn-2979-1
  CVE-2016-0758, CVE-2016-3713

Package Information:
  https://launchpad.net/ubuntu/+source/linux-lts-xenial/4.4.0-22.40~14.04.1

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