=========================================================================Ubuntu Security Notice USN-2848-1
December 19, 2015

linux 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: Linux kernel

Details:

Felix Wilhelm discovered a race condition in the Xen paravirtualized
drivers which can cause double fetch vulnerabilities. An attacker in the
paravirtualized guest could exploit this flaw to cause a denial of service
(crash the host) or potentially execute arbitrary code on the host.
(CVE-2015-8550)

Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not
perform sanity checks on the device's state. An attacker could exploit this
flaw to cause a denial of service (NULL dereference) on the host.
(CVE-2015-8551)

Konrad Rzeszutek Wilk discovered the Xen PCI backend driver does not
perform sanity checks on the device's state. An attacker could exploit this
flaw to cause a denial of service by flooding the logging system with
WARN() messages causing the initial domain to exhaust disk space.
(CVE-2015-8552)

Jann Horn discovered a ptrace issue with user namespaces in the Linux
kernel. The namespace owner could potentially exploit this flaw by ptracing
a root owned process entering the user namespace to elevate its privileges
and potentially gain access outside of the namespace.
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1527374)

Update instructions:

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

Ubuntu 14.04 LTS:
  linux-image-3.13.0-74-generic   3.13.0-74.118
  linux-image-3.13.0-74-generic-lpae  3.13.0-74.118
  linux-image-3.13.0-74-lowlatency  3.13.0-74.118
  linux-image-3.13.0-74-powerpc-e500  3.13.0-74.118
  linux-image-3.13.0-74-powerpc-e500mc  3.13.0-74.118
  linux-image-3.13.0-74-powerpc-smp  3.13.0-74.118
  linux-image-3.13.0-74-powerpc64-emb  3.13.0-74.118
  linux-image-3.13.0-74-powerpc64-smp  3.13.0-74.118

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-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  https://ubuntu.com/security/notices/USN-2848-1
  CVE-2015-8550, CVE-2015-8551, CVE-2015-8552, https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1527374

Package Information:
  https://launchpad.net/ubuntu/+source/linux/3.13.0-74.118