==========================================================================
Ubuntu Security Notice USN-4006-2
June 04, 2019

linux-hwe vulnerability
==========================================================================

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

- Ubuntu 18.04 LTS

Summary:

A system hardening measure could be bypassed.

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

Details:

USN-4006-1 fixed a vulnerability in the Linux kernel for Ubuntu 18.10.
This update provides the corresponding updates for the Linux Hardware
Enablement (HWE) kernel from Ubuntu 18.10 for Ubuntu 18.04 LTS.

Federico Manuel Bento discovered that the Linux kernel did not properly
apply Address Space Layout Randomization (ASLR) in some situations for
setuid a.out binaries. A local attacker could use this to improve the
chances of exploiting an existing vulnerability in a setuid a.out binary.

As a hardening measure, this update disables a.out support.

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-4.18.0-21-generic   4.18.0-21.22~18.04.1
  linux-image-4.18.0-21-generic-lpae  4.18.0-21.22~18.04.1
  linux-image-4.18.0-21-lowlatency  4.18.0-21.22~18.04.1
  linux-image-4.18.0-21-snapdragon  4.18.0-21.22~18.04.1
  linux-image-generic-hwe-18.04   4.18.0.21.71
  linux-image-generic-lpae-hwe-18.04  4.18.0.21.71
  linux-image-lowlatency-hwe-18.04  4.18.0.21.71
  linux-image-snapdragon-hwe-18.04  4.18.0.21.71

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/4006-2
  https://usn.ubuntu.com/4006-1
  CVE-2019-11191

Package Information:
  https://launchpad.net/ubuntu/+source/linux-hwe/4.18.0-21.22~18.04.1