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

19 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://bugs.launchpad.net/bugs/1527374, CVE-2015-8709)

Update instructions

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

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: https://wiki.ubuntu.com/Security/Upgrades.

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