Ubuntu 18.04 LTS USN-3740-1 Critical: Kernel Memory Exposure Threat

ubuntu

August 14, 2018

Several security issues were fixed in the Linux kernel.

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-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-kvm: Linux kernel for cloud environments

- linux-oem: Linux kernel for OEM processors- linux-raspi2: Linux kernel for Raspberry Pi 2

Details:

It was discovered that memory present in the L1 data cache of an Intel CPU

core may be exposed to a malicious process that is executing on the CPU

core. This vulnerability is also known as L1 Terminal Fault (L1TF). A local

attacker in a guest virtual machine could use this to expose sensitive

information (memory from other guests or the host OS). (CVE-2018-3646)

It was discovered that memory present in the L1 data cache of an Intel CPU

core may be exposed to a malicious process that is executing on the CPU

core. This vulnerability is also known...

Read the Full Advisory

Topics Covered

security advisory critical Ubuntu kernel Denial of Service memory exposure L1 Terminal Fault

Update Instructions

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1015-oem     4.15.0.1015.17
  linux-image-4.15.0-1017-gcp     4.15.0-1017.18
  linux-image-4.15.0-1019-aws     4.15.0-1019.19
  linux-image-4.15.0-1019-kvm     4.15.0-1019.19
  linux-image-4.15.0-1020-raspi2  4.15.0-1020.22
  linux-image-4.15.0-1021-azure   4.15.0.1021.21
  linux-image-4.15.0-32-generic   4.15.0-32.35
  linux-image-4.15.0-32-generic-lpae  4.15.0-32.35
  linux-image-4.15.0-32-lowlatency  4.15.0-32.35
  linux-image-4.15.0-32-snapdragon  4.15.0-32.35
  linux-image-aws                 4.15.0.1019.19
  linux-image-azure               4.15.0.1021.21
  linux-image-azure-edge          4.15.0.1021.21
  linux-image-gcp                 4.15.0.1017.19
  linux-image-generic             4.15.0.32.34
  linux-image-generic-lpae        4.15.0.32.34
  linux-image-gke                 4.15.0.1017.19
  linux-image-kvm                 4.15.0.1019.19
  linux-image-lowlatency          4.15.0.32.34
  linux-image-oem                 4.15.0.1015.17
  linux-image-raspi2              4.15.0.1020.18
  linux-image-snapdragon          4.15.0.32.34

Please note that the recommended mitigation for CVE-2018-3646 involves
updating processor microcode in addition to updating the kernel;
however, the kernel includes a fallback for processors that have not
received microcode updates.

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.