7.2 - USN-2979-1

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in the kernel.

Software Description: - linux: Linux kernel

Details:

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 16.04 LTS:
linux-image-4.4.0-22-generic 4.4.0-22.40
linux-image-4.4.0-22-generic-lpae 4.4.0-22.40
linux-image-4.4.0-22-lowlatency 4.4.0-22.40
linux-image-4.4.0-22-powerpc-e500mc 4.4.0-22.40
linux-image-4.4.0-22-powerpc-smp 4.4.0-22.40
linux-image-4.4.0-22-powerpc64-emb 4.4.0-22.40
linux-image-4.4.0-22-powerpc64-smp 4.4.0-22.40

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

Package Information:
https://launchpad.net/ubuntu/+source/linux/4.4.0-22.40