[USN-3652-1] Linux kernel vulnerability

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-3652-1
May 22, 2018

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oem vulnerability
==========================================================================

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

- Ubuntu 18.04 LTS

Summary:

The system could be made to expose sensitive information.

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

Details:

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.

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1008-gcp     4.15.0-1008.8
  linux-image-4.15.0-1009-aws     4.15.0-1009.9
  linux-image-4.15.0-1010-kvm     4.15.0-1010.10
  linux-image-4.15.0-22-generic   4.15.0-22.24
  linux-image-4.15.0-22-generic-lpae  4.15.0-22.24
  linux-image-4.15.0-22-lowlatency  4.15.0-22.24
  linux-image-aws                 4.15.0.1009.9
  linux-image-azure               4.15.0.1012.12
  linux-image-azure-edge          4.15.0.1012.12
  linux-image-gcp                 4.15.0.1008.10
  linux-image-generic             4.15.0.22.23
  linux-image-generic-lpae        4.15.0.22.23
  linux-image-gke                 4.15.0.1008.10
  linux-image-kvm                 4.15.0.1010.10
  linux-image-lowlatency          4.15.0.22.23
  linux-image-oem                 4.15.0.1006.8

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 users
of 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.

References:
  https://usn.ubuntu.com/usn/usn-3652-1
  CVE-2018-3639, https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/Variant4

Package Information:
  https://launchpad.net/ubuntu/+source/linux/4.15.0-22.24
  https://launchpad.net/ubuntu/+source/linux-aws/4.15.0-1009.9
  https://launchpad.net/ubuntu/+source/linux-azure/4.15.0-1012.12
  https://launchpad.net/ubuntu/+source/linux-gcp/4.15.0-1008.8
  https://launchpad.net/ubuntu/+source/linux-kvm/4.15.0-1010.10
  https://launchpad.net/ubuntu/+source/linux-oem/4.15.0-1006.9

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