USN-3652-1: Linux kernel vulnerability

22 May 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

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

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