USN-3903-2: Linux kernel (HWE) vulnerabilities

6 March 2019

linux-hwe, linux-azure vulnerabilities

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

  • Ubuntu 18.04 LTS

Summary

Several security issues were fixed in the Linux kernel.

Software Description

  • linux-azure - Linux kernel for Microsoft Azure Cloud systems
  • linux-hwe - Linux hardware enablement (HWE) kernel

Details

USN-3903-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.10. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.10 for Ubuntu 18.04 LTS.

Jason Wang discovered that the vhost net driver in the Linux kernel contained an out of bounds write vulnerability. An attacker in a guest virtual machine could use this to cause a denial of service (host system crash) or possibly execute arbitrary code in the host kernel. (CVE-2018-16880)

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)

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 18.04 LTS
linux-image-4.18.0-1013-azure - 4.18.0-1013.13~18.04.1
linux-image-4.18.0-16-generic - 4.18.0-16.17~18.04.1
linux-image-4.18.0-16-generic-lpae - 4.18.0-16.17~18.04.1
linux-image-4.18.0-16-lowlatency - 4.18.0-16.17~18.04.1
linux-image-4.18.0-16-snapdragon - 4.18.0-16.17~18.04.1
linux-image-azure - 4.18.0.1013.12
linux-image-generic-hwe-18.04 - 4.18.0.16.66
linux-image-generic-lpae-hwe-18.04 - 4.18.0.16.66
linux-image-lowlatency-hwe-18.04 - 4.18.0.16.66
linux-image-snapdragon-hwe-18.04 - 4.18.0.16.66

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