=========================================================================
Ubuntu Security Notice USN-4031-1
June 24, 2019

linux, linux-hwe vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 19.04
- Ubuntu 18.10
- Ubuntu 18.04 LTS

Summary:

64-Bit PowerPC systems could be made to expose sensitive information.

Software Description:
- linux: Linux kernel
- linux-hwe: Linux hardware enablement (HWE) kernel

Details:

It was discovered that the Linux kernel did not properly separate certain
memory mappings when creating new userspace processes on 64-bit Power
(ppc64el) systems. A local attacker could use this to access memory
contents or cause memory corruption of other processes on the system.

Update instructions:

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

Ubuntu 19.04:
  linux-image-5.0.0-19-generic    5.0.0-19.20
  linux-image-generic             5.0.0.19.20
  linux-image-virtual             5.0.0.19.20

Ubuntu 18.10:
  linux-image-4.18.0-24-generic   4.18.0-24.25
  linux-image-generic             4.18.0.24.25
  linux-image-powerpc-e500mc      4.18.0.24.25
  linux-image-powerpc-smp         4.18.0.24.25
  linux-image-powerpc64-emb       4.18.0.24.25
  linux-image-powerpc64-smp       4.18.0.24.25
  linux-image-virtual             4.18.0.24.25

Ubuntu 18.04 LTS:
  linux-image-4.18.0-24-generic   4.18.0-24.25~18.04.1
  linux-image-generic-hwe-18.04   4.18.0.24.74
  linux-image-virtual-hwe-18.04   4.18.0.24.74

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://usn.ubuntu.com/4031-1
  CVE-2019-12817

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.0.0-19.20
  https://launchpad.net/ubuntu/+source/linux/4.18.0-24.25
  https://launchpad.net/ubuntu/+source/linux-hwe/4.18.0-24.25~18.04.1