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Ubuntu Security Notice USN-4255-2
January 28, 2020

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-aws-hwe: Linux kernel for Amazon Web Services (AWS-HWE) systems
- linux-hwe: Linux hardware enablement (HWE) kernel

Details:

USN-4255-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04
LTS. This update provides the corresponding updates for the Linux
Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu
16.04 LTS.

It was discovered that the Linux kernel did not properly clear data
structures on context switches for certain Intel graphics processors. A
local attacker could use this to expose sensitive information.
(CVE-2019-14615)

It was discovered that a race condition can lead to a use-after-free while
destroying GEM contexts in the i915 driver for the Linux kernel. A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2020-7053)

Update instructions:

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

Ubuntu 16.04 LTS:
  linux-image-4.15.0-1058-aws     4.15.0-1058.60~16.04.1
  linux-image-4.15.0-76-generic   4.15.0-76.86~16.04.1
  linux-image-4.15.0-76-generic-lpae  4.15.0-76.86~16.04.1
  linux-image-4.15.0-76-lowlatency  4.15.0-76.86~16.04.1
  linux-image-aws-hwe             4.15.0.1058.58
  linux-image-generic-hwe-16.04   4.15.0.76.96
  linux-image-generic-lpae-hwe-16.04  4.15.0.76.96
  linux-image-lowlatency-hwe-16.04  4.15.0.76.96
  linux-image-oem                 4.15.0.76.96
  linux-image-virtual-hwe-16.04   4.15.0.76.96

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/4255-2
  https://usn.ubuntu.com/4255-1
  CVE-2019-14615, CVE-2020-7053

Package Information:
  https://launchpad.net/ubuntu/+source/linux-aws-hwe/4.15.0-1058.60~16.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-76.86~16.04.1