[USN-3468-3] Linux kernel (GCP) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-3468-3
October 31, 2017

linux-gcp vulnerabilities
==========================================================================

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

Details:

It was discovered that the KVM subsystem in the Linux kernel did not
properly bound guest IRQs. A local attacker in a guest VM could use this to
cause a denial of service (host system crash). (CVE-2017-1000252)

It was discovered that the Flash-Friendly File System (f2fs) implementation
in the Linux kernel did not properly validate superblock metadata. A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2017-10663)

Anthony Perard discovered that the Xen virtual block driver did not
properly initialize some data structures before passing them to user space.
A local attacker in a guest VM could use this to expose sensitive
information from the host OS or other guest VMs. (CVE-2017-10911)

It was discovered that a use-after-free vulnerability existed in the POSIX
message queue implementation in the Linux kernel. A local attacker could
use this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2017-11176)

Dave Chinner discovered that the XFS filesystem did not enforce that the
realtime inode flag was settable only on filesystems on a realtime device.
A local attacker could use this to cause a denial of service (system
crash). (CVE-2017-14340)

Update instructions:

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

Ubuntu 16.04 LTS:
  linux-image-4.10.0-1008-gcp     4.10.0-1008.8
  linux-image-gcp                 4.10.0.1008.10

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:
  https://www.ubuntu.com/usn/usn-3468-3
  https://www.ubuntu.com/usn/usn-3468-1
  CVE-2017-1000252, CVE-2017-10663, CVE-2017-10911, CVE-2017-11176,
  CVE-2017-14340

Package Information:
  https://launchpad.net/ubuntu/+source/linux-gcp/4.10.0-1008.8

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