==========================================================================
Ubuntu Security Notice USN-4068-2
July 23, 2019

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

Details:

USN-4068-1 fixed vulnerabilities in the Linux kernel for Ubuntu
18.04 LTS. This update provides the corresponding updates for the
Linux Hardware Enablement (HWE) kernel from Ubuntu 18.04 for Ubuntu
16.04 LTS.

Adam Zabrocki discovered that the Intel i915 kernel mode graphics driver in
the Linux kernel did not properly restrict mmap() ranges in some
situations. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2019-11085)

It was discovered that a race condition leading to a use-after-free existed
in the Reliable Datagram Sockets (RDS) protocol implementation in the Linux
kernel. The RDS protocol is blacklisted by default in Ubuntu. If enabled, a
local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2019-11815)

It was discovered that the ext4 file system implementation in the Linux
kernel did not properly zero out memory in some situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2019-11833)

It was discovered that the Bluetooth Human Interface Device Protocol (HIDP)
implementation in the Linux kernel did not properly verify strings were
NULL terminated in certain situations. A local attacker could use this to
expose sensitive information (kernel memory). (CVE-2019-11884)

Update instructions:

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

Ubuntu 16.04 LTS:
  linux-image-4.15.0-1037-gcp     4.15.0-1037.39~16.04.1
  linux-image-4.15.0-55-generic   4.15.0-55.60~16.04.2
  linux-image-4.15.0-55-generic-lpae  4.15.0-55.60~16.04.2
  linux-image-4.15.0-55-lowlatency  4.15.0-55.60~16.04.2
  linux-image-gcp                 4.15.0.1037.51
  linux-image-generic-hwe-16.04   4.15.0.55.76
  linux-image-generic-lpae-hwe-16.04  4.15.0.55.76
  linux-image-gke                 4.15.0.1037.51
  linux-image-lowlatency-hwe-16.04  4.15.0.55.76
  linux-image-oem                 4.15.0.55.76
  linux-image-virtual-hwe-16.04   4.15.0.55.76

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://usn.ubuntu.com/4068-2
  https://usn.ubuntu.com/4068-1
  CVE-2019-11085, CVE-2019-11815, CVE-2019-11833, CVE-2019-11884

Package Information:
  https://launchpad.net/ubuntu/+source/linux-gcp/4.15.0-1037.39~16.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe/4.15.0-55.60~16.04.2