A Linux kernel security update has been released for Ubuntu 18.04 LTS and 20.04 LTS.

USN-4658-1: Linux kernel vulnerabilities

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Ubuntu Security Notice USN-4658-1
December 02, 2020

linux, linux-aws, linux-aws-5.4, linux-azure, linux-azure-5.4, linux-gcp,
linux-gcp-5.4, linux-hwe-5.4, linux-kvm, linux-oracle, linux-oracle-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: 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-aws-5.4: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure-5.4: Linux kernel for Microsoft Azure cloud systems
- linux-gcp-5.4: Linux kernel for Google Cloud Platform (GCP) systems
- linux-hwe-5.4: Linux hardware enablement (HWE) kernel
- linux-oracle-5.4: Linux kernel for Oracle Cloud systems

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)

It was discovered that the frame buffer implementation in the Linux kernel
did not properly handle some edge cases in software scrollback. A local
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2020-14390)

It was discovered that the netfilter connection tracker for netlink 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).
(CVE-2020-25211)

It was discovered that the Rados block device (rbd) driver in the Linux
kernel did not properly perform privilege checks for access to rbd devices
in some situations. A local attacker could use this to map or unmap rbd
block devices. (CVE-2020-25284)

It was discovered that the HDLC PPP implementation in the Linux kernel did
not properly validate input in some situations. A local attacker could use
this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2020-25643)

It was discovered that the GENEVE tunnel implementation in the Linux kernel
when combined with IPSec did not properly select IP routes in some
situations. An attacker could use this to expose sensitive information
(unencrypted network traffic). (CVE-2020-25645)

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 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 20.04 LTS:
linux-image-5.4.0-1028-kvm 5.4.0-1028.29
linux-image-5.4.0-1030-aws 5.4.0-1030.31
linux-image-5.4.0-1030-gcp 5.4.0-1030.32
linux-image-5.4.0-1030-oracle 5.4.0-1030.32
linux-image-5.4.0-1032-azure 5.4.0-1032.33
linux-image-5.4.0-56-generic 5.4.0-56.62
linux-image-5.4.0-56-generic-lpae 5.4.0-56.62
linux-image-5.4.0-56-lowlatency 5.4.0-56.62
linux-image-aws 5.4.0.1030.31
linux-image-azure 5.4.0.1032.30
linux-image-gcp 5.4.0.1030.38
linux-image-generic 5.4.0.56.59
linux-image-generic-hwe-20.04 5.4.0.56.59
linux-image-generic-lpae 5.4.0.56.59
linux-image-generic-lpae-hwe-20.04 5.4.0.56.59
linux-image-gke 5.4.0.1030.38
linux-image-kvm 5.4.0.1028.26
linux-image-lowlatency 5.4.0.56.59
linux-image-lowlatency-hwe-20.04 5.4.0.56.59
linux-image-oem 5.4.0.56.59
linux-image-oem-osp1 5.4.0.56.59
linux-image-oracle 5.4.0.1030.27
linux-image-virtual 5.4.0.56.59
linux-image-virtual-hwe-20.04 5.4.0.56.59

Ubuntu 18.04 LTS:
linux-image-5.4.0-1030-aws 5.4.0-1030.31~18.04.1
linux-image-5.4.0-1030-gcp 5.4.0-1030.32~18.04.1
linux-image-5.4.0-1030-oracle 5.4.0-1030.32~18.04.1
linux-image-5.4.0-1032-azure 5.4.0-1032.33~18.04.1
linux-image-5.4.0-56-generic 5.4.0-56.62~18.04.1
linux-image-5.4.0-56-generic-lpae 5.4.0-56.62~18.04.1
linux-image-5.4.0-56-lowlatency 5.4.0-56.62~18.04.1
linux-image-aws 5.4.0.1030.15
linux-image-azure 5.4.0.1032.14
linux-image-gcp 5.4.0.1030.18
linux-image-generic-hwe-18.04 5.4.0.56.62~18.04.50
linux-image-generic-lpae-hwe-18.04 5.4.0.56.62~18.04.50
linux-image-lowlatency-hwe-18.04 5.4.0.56.62~18.04.50
linux-image-oem-osp1 5.4.0.56.62~18.04.50
linux-image-oracle 5.4.0.1030.14
linux-image-snapdragon-hwe-18.04 5.4.0.56.62~18.04.50
linux-image-virtual-hwe-18.04 5.4.0.56.62~18.04.50

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/4658-1
CVE-2020-0423, CVE-2020-10135, CVE-2020-14351, CVE-2020-14390,
CVE-2020-25211, CVE-2020-25284, CVE-2020-25643, CVE-2020-25645,
CVE-2020-25705, CVE-2020-28915, CVE-2020-4788

Package Information:
  https://launchpad.net/ubuntu/+source/linux/5.4.0-56.62
  https://launchpad.net/ubuntu/+source/linux-aws/5.4.0-1030.31
  https://launchpad.net/ubuntu/+source/linux-azure/5.4.0-1032.33
  https://launchpad.net/ubuntu/+source/linux-gcp/5.4.0-1030.32
  https://launchpad.net/ubuntu/+source/linux-kvm/5.4.0-1028.29
  https://launchpad.net/ubuntu/+source/linux-oracle/5.4.0-1030.32
  https://launchpad.net/ubuntu/+source/linux-aws-5.4/5.4.0-1030.31~18.04.1
  https://launchpad.net/ubuntu/+source/linux-azure-5.4/5.4.0-1032.33~18.04.1
  https://launchpad.net/ubuntu/+source/linux-gcp-5.4/5.4.0-1030.32~18.04.1
  https://launchpad.net/ubuntu/+source/linux-hwe-5.4/5.4.0-56.62~18.04.1
  https://launchpad.net/ubuntu/+source/linux-oracle-5.4/5.4.0-1030.32~18.04.1