==========================================================================
Ubuntu Security Notice USN-5106-1
October 06, 2021

linux-oem-5.10 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-5.10: Linux kernel for OEM systems

Details:

Valentina Palmiotti discovered that the io_uring subsystem in the Linux
kernel could be coerced to free adjacent memory. A local attacker could use
this to execute arbitrary code. (CVE-2021-41073)

It was discovered that the Linux kernel did not properly enforce certain
types of entries in the Secure Boot Forbidden Signature Database (aka dbx)
protection mechanism. An attacker could use this to bypass UEFI Secure Boot
restrictions. (CVE-2020-26541)

It was discovered that the KVM hypervisor implementation in the Linux
kernel did not properly perform reference counting in some situations,
leading to a use-after-free vulnerability. An attacker who could start and
control a VM could possibly use this to expose sensitive information or
execute arbitrary code. (CVE-2021-22543)

Murray McAllister discovered that the joystick device interface in the
Linux kernel did not properly validate data passed via an ioctl(). A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code on systems with a joystick device
registered. (CVE-2021-3612)

It was discovered that the Virtio console implementation in the Linux
kernel did not properly validate input lengths in some situations. A local
attacker could possibly use this to cause a denial of service (system
crash). (CVE-2021-38160)

Michael Wakabayashi discovered that the NFSv4 client implementation in the
Linux kernel did not properly order connection setup operations. An
attacker controlling a remote NFS server could use this to cause a denial
of service on the client. (CVE-2021-38199)

Update instructions:

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

Ubuntu 20.04 LTS:
  linux-image-5.10.0-1049-oem     5.10.0-1049.51
  linux-image-oem-20.04           5.10.0.1049.51
  linux-image-oem-20.04b          5.10.0.1049.51

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-5106-1
  CVE-2020-26541, CVE-2021-22543, CVE-2021-3612, CVE-2021-38160,
  CVE-2021-38199, CVE-2021-41073

Package Information:
  https://launchpad.net/ubuntu/+source/linux-oem-5.10/5.10.0-1049.51