USN-3836-1: Linux kernel vulnerabilities

USN-3836-1: Linux kernel vulnerabilities

linux, linux-gcp, linux-kvm, linux-raspi2 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 – Linux kernel
• linux-gcp – Linux kernel for Google Cloud Platform (GCP) systems
• linux-kvm – Linux kernel for cloud environments
• linux-raspi2 – Linux kernel for Raspberry Pi 2

Details

Jann Horn discovered that the Linux kernel mishandles mapping UID or GID
ranges inside nested user namespaces in some situations. A local attacker
could use this to bypass access controls on resources outside the
namespace. (CVE-2018-18955)

Philipp Wendler discovered that the overlayfs implementation in the Linux
kernel did not properly verify the directory contents permissions from
within a unprivileged user namespace. A local attacker could use this to
expose sensitive information (protected file names). (CVE-2018-6559)

Update instructions

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

Ubuntu 18.04 LTS

linux-image-4.15.0-1025-gcp – 4.15.0-1025.26

linux-image-4.15.0-1027-kvm – 4.15.0-1027.27

linux-image-4.15.0-1029-raspi2 – 4.15.0-1029.31

linux-image-4.15.0-42-generic – 4.15.0-42.45

linux-image-4.15.0-42-generic-lpae – 4.15.0-42.45

linux-image-4.15.0-42-lowlatency – 4.15.0-42.45

linux-image-4.15.0-42-snapdragon – 4.15.0-42.45

linux-image-gcp – 4.15.0.1025.27

linux-image-generic – 4.15.0.42.44

linux-image-generic-lpae – 4.15.0.42.44

linux-image-gke – 4.15.0.1025.27

linux-image-kvm – 4.15.0.1027.27

linux-image-lowlatency – 4.15.0.42.44

linux-image-raspi2 – 4.15.0.1029.27

linux-image-snapdragon – 4.15.0.42.44

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

• CVE-2018-18955
• CVE-2018-6559

Source: USN-3836-1: Linux kernel vulnerabilities