USN-2847-1: Linux kernel (Trusty HWE) vulnerabilities

Ubuntu Security Notice USN-2847-1

19th December, 2015

linux-lts-trusty vulnerabilities

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

• Ubuntu 12.04 LTS

Summary

Several security issues were fixed in the kernel.

Software description

• linux-lts-trusty - Linux hardware enablement kernel from Trusty

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.
(http://ift.tt/1NvLaK8)

Update instructions

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

Ubuntu 12.04 LTS:

linux-image-3.13.0-74-generic 3.13.0-74.118~precise1

linux-image-3.13.0-74-generic-lpae 3.13.0-74.118~precise1

To update your system, please follow these instructions: http://ift.tt/17VXqjU.

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

CVE-2015-8550, CVE-2015-8551, CVE-2015-8552, CVE-2015-NNN2

from Ubuntu Security Notices http://ift.tt/1QBhi2v