USN-3833-1: Linux kernel (AWS) vulnerabilities

30 November 2018

Several security issues were fixed in the Linux kernel.

Releases

Packages

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

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

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.

Related notices

  • USN-3832-1: linux-image-4.18.0-1006-aws, linux-image-aws, linux-aws
  • USN-3836-1: linux-image-unsigned-4.15.0-42-lowlatency, linux-kvm, linux-image-4.15.0-42-snapdragon, linux-image-unsigned-4.15.0-1025-gcp, linux-raspi2, linux-image-4.15.0-42-generic, linux-image-4.15.0-1029-raspi2, linux-image-4.15.0-1027-kvm, linux-image-4.15.0-42-generic-lpae, linux-image-unsigned-4.15.0-42-generic, linux-image-4.15.0-42-lowlatency, linux-gcp, linux
  • USN-3835-1: linux-image-4.18.0-12-generic, linux-image-raspi2, linux-image-4.18.0-1005-kvm, linux-image-gke, linux-image-gcp, linux-raspi2, linux-image-generic-lpae, linux-image-kvm, linux-gcp, linux-image-4.18.0-1007-raspi2, linux-image-4.18.0-12-snapdragon, linux-image-generic, linux-image-4.18.0-12-generic-lpae, linux-image-lowlatency, linux-image-4.18.0-1004-gcp, linux-kvm, linux-image-4.18.0-12-lowlatency, linux, linux-image-snapdragon
  • USN-3836-2: linux-image-unsigned-4.15.0-42-lowlatency, linux-image-unsigned-4.15.0-1025-gcp, linux-hwe, linux-image-4.15.0-42-generic, linux-image-4.15.0-42-generic-lpae, linux-image-unsigned-4.15.0-42-generic, linux-image-4.15.0-42-lowlatency, linux-gcp