A Linux kernel security update is available for Ubuntu Linux 18.04 LTS.

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Ubuntu Security Notice USN-4255-1
January 28, 2020

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

- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-oem: Linux kernel for OEM processors

Details:

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 18.04 LTS:
linux-image-4.15.0-1058-aws 4.15.0-1058.60
linux-image-4.15.0-1067-oem 4.15.0-1067.77
linux-image-4.15.0-76-generic 4.15.0-76.86
linux-image-4.15.0-76-generic-lpae 4.15.0-76.86
linux-image-4.15.0-76-lowlatency 4.15.0-76.86
linux-image-aws 4.15.0.1058.59
linux-image-aws-lts-18.04 4.15.0.1058.59
linux-image-generic 4.15.0.76.78
linux-image-generic-lpae 4.15.0.76.78
linux-image-lowlatency 4.15.0.76.78
linux-image-oem 4.15.0.1067.71
linux-image-powerpc-e500mc 4.15.0.76.78
linux-image-powerpc-smp 4.15.0.76.78
linux-image-powerpc64-emb 4.15.0.76.78
linux-image-powerpc64-smp 4.15.0.76.78
linux-image-virtual 4.15.0.76.78

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/4255-1
CVE-2019-14615, CVE-2020-7053

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.15.0-76.86
  https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1058.60
  https://launchpad.net/ubuntu/+source/linux-oem/4.15.0-1067.77