==========================================================================
Ubuntu Security Notice USN-5579-1
August 24, 2022

linux, linux-kvm, linux-lts-xenial vulnerabilities
==========================================================================

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-kvm: Linux kernel for cloud environments
- linux-lts-xenial: Linux hardware enablement kernel from Xenial for Trusty

Details:

Roger Pau Monné discovered that the Xen virtual block driver in the 
Linux kernel did not properly initialize memory pages to be used for 
shared communication with the backend. A local attacker could use this 
to expose sensitive information (guest kernel memory). (CVE-2022-26365)

Roger Pau Monné discovered that the Xen paravirtualization frontend in 
the Linux kernel did not properly initialize memory pages to be used for 
shared communication with the backend. A local attacker could use this 
to expose sensitive information (guest kernel memory). (CVE-2022-33740)

It was discovered that the Xen paravirtualization frontend in the Linux
kernel incorrectly shared unrelated data when communicating with certain
backends. A local attacker could use this to cause a denial of service
(guest crash) or expose sensitive information (guest kernel memory).
(CVE-2022-33741)

Update instructions:

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

Ubuntu 16.04 ESM:
   linux-image-4.4.0-1113-kvm      4.4.0-1113.123
   linux-image-4.4.0-233-generic   4.4.0-233.267
   linux-image-4.4.0-233-lowlatency  4.4.0-233.267
   linux-image-generic             4.4.0.233.239
   linux-image-kvm                 4.4.0.1113.110
   linux-image-lowlatency          4.4.0.233.239
   linux-image-virtual             4.4.0.233.239

Ubuntu 14.04 ESM:
   linux-image-4.4.0-233-generic   4.4.0-233.267~14.04.1
   linux-image-4.4.0-233-lowlatency  4.4.0-233.267~14.04.1
   linux-image-generic-lts-xenial  4.4.0.233.202
   linux-image-lowlatency-lts-xenial  4.4.0.233.202
   linux-image-virtual-lts-xenial  4.4.0.233.202

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://ubuntu.com/security/notices/USN-5579-1
   CVE-2022-26365, CVE-2022-33740, CVE-2022-33741