USN-3901-2: Linux kernel (HWE) vulnerabilities

5 March 2019

linux-hwe, linux-aws-hwe, linux-azure, linux-gcp, linux-oracle vulnerabilities

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

  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS

Summary

Several security issues were fixed in the Linux kernel.

Software Description

  • linux-aws-hwe - Linux kernel for Amazon Web Services (AWS-HWE) systems
  • 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-oracle - Linux kernel for Oracle Cloud systems

Details

USN-3901-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 LTS for Ubuntu 16.04 LTS.

Jann Horn discovered that the userfaultd implementation in the Linux kernel did not properly restrict access to certain ioctls. A local attacker could use this possibly to modify files. (CVE-2018-18397)

It was discovered that the crypto subsystem of the Linux kernel leaked uninitialized memory to user space in some situations. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2018-19854)

Jann Horn discovered a race condition in the fork() system call in the Linux kernel. A local attacker could use this to gain access to services that cache authorizations. (CVE-2019-6133)

Update instructions

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

Ubuntu 16.04 LTS
linux-image-4.15.0-1009-oracle - 4.15.0-1009.11~16.04.1
linux-image-4.15.0-1028-gcp - 4.15.0-1028.29~16.04.1
linux-image-4.15.0-1033-aws - 4.15.0-1033.35~16.04.1
linux-image-4.15.0-1040-azure - 4.15.0-1040.44
linux-image-4.15.0-46-generic - 4.15.0-46.49~16.04.1
linux-image-4.15.0-46-generic-lpae - 4.15.0-46.49~16.04.1
linux-image-4.15.0-46-lowlatency - 4.15.0-46.49~16.04.1
linux-image-aws-hwe - 4.15.0.1033.34
linux-image-azure - 4.15.0.1040.44
linux-image-gcp - 4.15.0.1028.42
linux-image-generic-hwe-16.04 - 4.15.0.46.67
linux-image-generic-lpae-hwe-16.04 - 4.15.0.46.67
linux-image-gke - 4.15.0.1028.42
linux-image-lowlatency-hwe-16.04 - 4.15.0.46.67
linux-image-oem - 4.15.0.46.67
linux-image-oracle - 4.15.0.1009.3
Ubuntu 14.04 LTS
linux-image-4.15.0-1040-azure - 4.15.0-1040.44~14.04.1
linux-image-azure - 4.15.0.1040.27

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

After a standard system update you need to reboot your computer to make all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have been given a new version number, which requires you to recompile and reinstall all third party kernel modules you might have installed. Unless you manually uninstalled the standard kernel metapackages (e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual, linux-powerpc), a standard system upgrade will automatically perform this as well.

References