Ubuntu 16.04 LTS USN-3653-2 Critical: Kernel Security Issues and Updates

ubuntu

May 22, 2018

Several security issues were addressed in the Linux kernel.

Summary

Several security issues were addressed in the Linux kernel.

Software Description:

- linux-azure: Linux kernel for Microsoft Azure Cloud systems

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

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

- linux-oem: Linux kernel for OEM processors

Details:

USN-3653-1 fixed vulnerabilities and added mitigations in the Linux

kernel for Ubuntu 17.10. This update provides the corresponding

updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu

17.10 for Ubuntu 16.04 LTS.

Jann Horn and Ken Johnson discovered that microprocessors utilizing

speculative execution of a memory read may allow unauthorized memory

reads via a sidechannel attack. This flaw is known as Spectre

Variant 4. A local attacker could use this to expose sensitive

information, including kernel memory. (CVE-2018-3639)

It was discovered that the netlink subsystem in the Linux kernel did not

properly restrict observations of netlink messages to the ap...

Read the Full Advisory

Topics Covered

security advisory denial of service critical Ubuntu kernel system crash memory exposure

Update Instructions

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

Ubuntu 16.04 LTS:
  linux-image-4.13.0-1017-gcp     4.13.0-1017.21
  linux-image-4.13.0-1018-azure   4.13.0-1018.21
  linux-image-4.13.0-1028-oem     4.13.0-1028.31
  linux-image-4.13.0-43-generic   4.13.0-43.48~16.04.1
  linux-image-4.13.0-43-generic-lpae  4.13.0-43.48~16.04.1
  linux-image-4.13.0-43-lowlatency  4.13.0-43.48~16.04.1
  linux-image-azure               4.13.0.1018.19
  linux-image-gcp                 4.13.0.1017.19
  linux-image-generic-hwe-16.04   4.13.0.43.62
  linux-image-generic-lpae-hwe-16.04  4.13.0.43.62
  linux-image-gke                 4.13.0.1017.19
  linux-image-lowlatency-hwe-16.04  4.13.0.43.62
  linux-image-oem                 4.13.0.1028.33

Please note that fully mitigating CVE-2018-3639 (Spectre Variant 4)
may require corresponding processor microcode/firmware updates or,
in virtual environments, hypervisor updates. On i386 and amd64
architectures, the SSBD feature is required to enable the kernel
mitigations. BIOS vendors will be making updates available for Intel
processors that implement SSBD and Ubuntu is working with Intel to
provide future microcode updates. Ubuntu users with a processor from
a different vendor should contact the vendor to identify necessary
firmware updates. Ubuntu provided corresponding QEMU updates for usersof self-hosted virtual environments in USN 3651-1. Ubuntu users in
cloud environments should contact the cloud provider to confirm that
the hypervisor has been updated to expose the new CPU features to
virtual machines.