[USN-3468-2] Linux kernel (HWE) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-3468-2
October 31, 2017

linux-hwe 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-hwe: Linux hardware enablement (HWE) kernel

Details:

USN-3468-1 fixed vulnerabilities in the Linux kernel for Ubuntu 17.04.
This update provides the corresponding updates for the Linux Hardware
Enablement (HWE) kernel from Ubuntu 17.04 for Ubuntu 16.04 LTS.

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-4.10.0-38-generic   4.10.0-38.42~16.04.1
  linux-image-4.10.0-38-generic-lpae  4.10.0-38.42~16.04.1
  linux-image-4.10.0-38-lowlatency  4.10.0-38.42~16.04.1
  linux-image-generic-hwe-16.04   4.10.0.38.40
  linux-image-generic-lpae-hwe-16.04  4.10.0.38.40
  linux-image-lowlatency-hwe-16.04  4.10.0.38.40

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-3468-2
  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-hwe/4.10.0-38.42~16.04.1

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