A Linux kernel regression update has been released for Ubuntu Linux 20.10.

USN-4659-2: Linux kernel regression

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Ubuntu Security Notice USN-4659-2
December 13, 2020

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oracle,
linux-raspi regression
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10

Summary:

USN-4659-1 introduced a regression in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oracle: Linux kernel for Oracle Cloud systems
- linux-raspi: Linux kernel for Raspberry Pi (V8) systems

Details:

USN-4659-1 fixed vulnerabilities in the Linux kernel. Unfortunately,
that update introduced a regression in the software raid10 driver
when used with fstrim that could lead to data corruption. This update
fixes the problem.

Original advisory details:

It was discovered that a race condition existed in the binder IPC
implementation in 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-2020-0423)

Daniele Antonioli, Nils Ole Tippenhauer, and Kasper Rasmussen discovered
that legacy pairing and secure-connections pairing authentication in the
Bluetooth protocol could allow an unauthenticated user to complete
authentication without pairing credentials via adjacent access. A
physically proximate attacker could use this to impersonate a previously
paired Bluetooth device. (CVE-2020-10135)

It was discovered that a race condition existed in the perf subsystem of
the Linux kernel, leading to a use-after-free vulnerability. An attacker
with access to the perf subsystem could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2020-14351)

Keyu Man discovered that the ICMP global rate limiter in the Linux kernel
could be used to assist in scanning open UDP ports. A remote attacker could
use to facilitate attacks on UDP based services that depend on source port
randomization. (CVE-2020-25705)

It was discovered that the KVM hypervisor in the Linux kernel did not
properly handle interrupts in certain situations. A local attacker in a
guest VM could possibly use this to cause a denial of service (host system
crash). (CVE-2020-27152)

It was discovered that the framebuffer implementation in the Linux kernel
did not properly perform range checks in certain situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2020-28915)

It was discovered that Power 9 processors could be coerced to expose
information from the L1 cache in certain situations. A local attacker could
use this to expose sensitive information. (CVE-2020-4788)

Update instructions:

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

Ubuntu 20.10:
linux-image-5.8.0-1010-raspi 5.8.0-1010.13
linux-image-5.8.0-1010-raspi-nolpae 5.8.0-1010.13
linux-image-5.8.0-1013-kvm 5.8.0-1013.14
linux-image-5.8.0-1013-oracle 5.8.0-1013.13
linux-image-5.8.0-1014-gcp 5.8.0-1014.14
linux-image-5.8.0-1015-azure 5.8.0-1015.16
linux-image-5.8.0-1016-aws 5.8.0-1016.17
linux-image-5.8.0-33-generic 5.8.0-33.36
linux-image-5.8.0-33-generic-64k 5.8.0-33.36
linux-image-5.8.0-33-generic-lpae 5.8.0-33.36
linux-image-5.8.0-33-lowlatency 5.8.0-33.36
linux-image-aws 5.8.0.1016.18
linux-image-azure 5.8.0.1015.15
linux-image-gcp 5.8.0.1014.14
linux-image-generic 5.8.0.33.38
linux-image-generic-64k 5.8.0.33.38
linux-image-generic-lpae 5.8.0.33.38
linux-image-gke 5.8.0.1014.14
linux-image-kvm 5.8.0.1013.15
linux-image-lowlatency 5.8.0.33.38
linux-image-oem-20.04 5.8.0.33.38
linux-image-oracle 5.8.0.1013.13
linux-image-raspi 5.8.0.1010.13
linux-image-raspi-nolpae 5.8.0.1010.13
linux-image-virtual 5.8.0.33.38

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/4659-2
  https://usn.ubuntu.com/4659-1
  https://launchpad.net/bugs/1907262

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.8.0-33.36
  https://launchpad.net/ubuntu/+source/linux-aws/5.8.0-1016.17
  https://launchpad.net/ubuntu/+source/linux-azure/5.8.0-1015.16
  https://launchpad.net/ubuntu/+source/linux-gcp/5.8.0-1014.14
  https://launchpad.net/ubuntu/+source/linux-kvm/5.8.0-1013.14
  https://launchpad.net/ubuntu/+source/linux-oracle/5.8.0-1013.13
  https://launchpad.net/ubuntu/+source/linux-raspi/5.8.0-1010.13