A Linux kernel (Raspberry Pi) security update has been released for Ubuntu Linux 18.04 LTS and 20.04 LTS.

USN-5267-3: Linux kernel (Raspberry Pi) vulnerabilities

=========================================================================
Ubuntu Security Notice USN-5267-3
February 17, 2022

linux-raspi, linux-raspi-5.4 vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-raspi: Linux kernel for Raspberry Pi systems
- linux-raspi-5.4: Linux kernel for Raspberry Pi systems

Details:

USN-5267-1 fixed vulnerabilities in the Linux kernel. This
update provides the corresponding updates for the Linux kernel
for Raspberry Pi devices.

Original advisory details:

It was discovered that the Bluetooth subsystem in the Linux kernel
contained a use-after-free vulnerability. A local attacker could use this
to cause a denial of service (system crash) or possibly execute arbitrary
code. (CVE-2021-3640)

Likang Luo discovered that a race condition existed in the Bluetooth
subsystem of the Linux kernel, leading to a use-after-free vulnerability. A
local attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2021-3752)

Luo Likang discovered that the FireDTV Firewire driver in the Linux kernel
did not properly perform bounds checking in some situations. A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2021-42739)

Update instructions:

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

Ubuntu 20.04 LTS:
linux-image-5.4.0-1052-raspi 5.4.0-1052.58
linux-image-raspi 5.4.0.1052.86
linux-image-raspi2 5.4.0.1052.86

Ubuntu 18.04 LTS:
linux-image-5.4.0-1052-raspi 5.4.0-1052.58~18.04.1
linux-image-raspi-hwe-18.04 5.4.0.1052.54

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-5267-3
  https://ubuntu.com/security/notices/USN-5267-1
CVE-2021-3640, CVE-2021-3752, CVE-2021-42739

Package Information:
  https://launchpad.net/ubuntu/+source/linux-raspi/5.4.0-1052.58
  https://launchpad.net/ubuntu/+source/linux-raspi-5.4/5.4.0-1052.58~18.04.1