1. Ubuntu Security Notices
  2. USN-3540-1

USN-3540-1: Linux kernel vulnerabilities

Publication date

23 January 2018

Overview

Several security issues were addressed in the Linux kernel.

Releases

Packages

  • linux - Linux kernel
  • linux-aws - Linux kernel for Amazon Web Services (AWS) systems
  • linux-euclid - Linux kernel for Intel Euclid systems

Details

Jann Horn discovered that microprocessors utilizing speculative
execution and branch prediction may allow unauthorized memory
reads via sidechannel attacks. This flaw is known as Spectre. A
local attacker could use this to expose sensitive information,
including kernel memory. This update provides mitigations for the
i386 (CVE-2017-5753 only), amd64, ppc64el, and s390x architectures.
(CVE-2017-5715, CVE-2017-5753)

USN-3522-1 mitigated CVE-2017-5754 (Meltdown) for the amd64
architecture in Ubuntu 16.04 LTS. This update provides the
corresponding mitigations for the ppc64el architecture. Original
advisory details:

Jann Horn discovered that microprocessors utilizing speculative
execution and indirect branch prediction may allow unauthorized memory
reads via sidechannel...

Jann Horn discovered that microprocessors utilizing speculative
execution and branch prediction may allow unauthorized memory
reads via sidechannel attacks. This flaw is known as Spectre. A
local attacker could use this to expose sensitive information,
including kernel memory. This update provides mitigations for the
i386 (CVE-2017-5753 only), amd64, ppc64el, and s390x architectures.
(CVE-2017-5715, CVE-2017-5753)

USN-3522-1 mitigated CVE-2017-5754 (Meltdown) for the amd64
architecture in Ubuntu 16.04 LTS. This update provides the
corresponding mitigations for the ppc64el architecture. Original
advisory details:

Jann Horn discovered that microprocessors utilizing speculative
execution and indirect branch prediction may allow unauthorized memory
reads via sidechannel attacks. This flaw is known as Meltdown. A local
attacker could use this to expose sensitive information, including
kernel memory. (CVE-2017-5754)

Update instructions

Please note that fully mitigating CVE-2017-5715 (Spectre Variant 2) requires corresponding processor microcode/firmware updates or, in virtual environments, hypervisor updates. On i386 and amd64 architectures, the IBRS and IBPB features are required to enable the kernel mitigations. Ubuntu is working with Intel and AMD to provide future microcode updates that implement IBRS and IBPB as they are made available. Ubuntu users with a processor from a different vendor should contact the vendor to identify necessary firmware updates. Ubuntu will provide corresponding QEMU updates in the future for users of self-hosted virtual environments in coordination with upstream QEMU. 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. After a standard system update you need to reboot your computer to make the necessary changes.

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
16.04 xenial linux-image-4.4.0-1049-aws –  4.4.0-1049.58
linux-image-4.4.0-112-generic –  4.4.0-112.135
linux-image-4.4.0-112-generic-lpae –  4.4.0-112.135
linux-image-4.4.0-112-lowlatency –  4.4.0-112.135
linux-image-4.4.0-112-powerpc-e500mc –  4.4.0-112.135
linux-image-4.4.0-112-powerpc-smp –  4.4.0-112.135
linux-image-4.4.0-112-powerpc64-emb –  4.4.0-112.135
linux-image-4.4.0-112-powerpc64-smp –  4.4.0-112.135
linux-image-4.4.0-9023-euclid –  4.4.0-9023.24

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References

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