A Linux kernel (OEM) security update has been released for Ubuntu Linux 20.04 LTS.

USN-5117-1: Linux kernel (OEM) vulnerabilities

=========================================================================
Ubuntu Security Notice USN-5117-1
October 20, 2021

linux-oem-5.13 vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-oem-5.13: Linux kernel for OEM systems

Details:

It was discovered that the btrfs file system in the Linux kernel did not
properly handle removing a non-existent device id. An attacker with
CAP_SYS_ADMIN could use this to cause a denial of service. (CVE-2021-3739)

It was discovered that the Qualcomm IPC Router protocol implementation in
the Linux kernel did not properly validate metadata in some situations. A
local attacker could use this to cause a denial of service (system crash)
or expose sensitive information. (CVE-2021-3743)

It was discovered that the virtual terminal (vt) device implementation in
the Linux kernel contained a race condition in its ioctl handling that led
to an out-of-bounds read vulnerability. A local attacker could possibly use
this to expose sensitive information. (CVE-2021-3753)

It was discovered that the Linux kernel did not properly account for the
memory usage of certain IPC objects. A local attacker could use this to
cause a denial of service (memory exhaustion). (CVE-2021-3759)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.13.0-1017-oem 5.13.0-1017.21
linux-image-oem-20.04c 5.13.0.1017.21

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-5117-1
CVE-2021-3739, CVE-2021-3743, CVE-2021-3753, CVE-2021-3759

Package Information:
  https://launchpad.net/ubuntu/+source/linux-oem-5.13/5.13.0-1017.21