USN-3541-2: Linux kernel (HWE) vulnerabilities
23 January 2018
linux-hwe, linux-azure, linux-gcp, linux-oem vulnerabilities
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 16.04 LTS
Several security issues were addressed in the Linux kernel.
- 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
USN-3541-1 addressed vulnerabilities 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 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-3523-2 mitigated CVE-2017-5754 (Meltdown) for the amd64 architecture in the Linux Hardware Enablement (HWE) kernel from Ubuntu 17.10 for 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)
The problem can be corrected by updating your system to the following package versions:
- Ubuntu 16.04 LTS
- linux-image-4.13.0-1006-azure - 4.13.0-1006.8
- linux-image-4.13.0-1007-gcp - 4.13.0-1007.10
- linux-image-4.13.0-1017-oem - 4.13.0-1017.18
- linux-image-4.13.0-31-generic - 4.13.0-31.34~16.04.1
- linux-image-4.13.0-31-lowlatency - 4.13.0-31.34~16.04.1
- linux-image-azure - 18.104.22.1686.7
- linux-image-gcp - 22.214.171.1247.9
- linux-image-generic-hwe-16.04 - 126.96.36.199.51
- linux-image-gke - 188.8.131.527.9
- linux-image-lowlatency-hwe-16.04 - 184.108.40.206.51
- linux-image-oem - 220.127.116.117.21
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
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 apply the necessary changes.