Ubuntu 20.04 and 20.10: USN-4910-1 Severe: Kernel Multiple Exploits

ubuntu

April 13, 2021

Several security issues were fixed in the Linux kernel.

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-raspi: Linux kernel for Raspberry Pi (V8) systems

- linux-hwe-5.8: Linux hardware enablement (HWE) kernel

Details:

Ryota Shiga discovered that the sockopt BPF hooks in the Linux kernel could

allow a user space program to probe for valid kernel addresses. A local

attacker could use this to ease exploitation of another kernel

vulnerability. (CVE-2021-20239)

It was discovered that the BPF verifier in the Linux kernel did not

properly handle signed add32 and sub integer overflows. A local attacker

could use this to cause a denial of service (system crash) or possib...

Read the Full Advisory

Topics Covered

security advisory denial of service critical issue kernel update code execution Ubuntu local exploit race condition kernel ubuntu system crash

Update Instructions

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

Ubuntu 20.10:
  linux-image-5.8.0-1020-raspi    5.8.0-1020.23
  linux-image-5.8.0-1020-raspi-nolpae  5.8.0-1020.23
  linux-image-5.8.0-1023-kvm      5.8.0-1023.25
  linux-image-5.8.0-1025-oracle   5.8.0-1025.26
  linux-image-5.8.0-1027-azure    5.8.0-1027.29
  linux-image-5.8.0-1027-gcp      5.8.0-1027.28
  linux-image-5.8.0-1028-aws      5.8.0-1028.30
  linux-image-5.8.0-49-generic    5.8.0-49.55
  linux-image-5.8.0-49-generic-64k  5.8.0-49.55
  linux-image-5.8.0-49-generic-lpae  5.8.0-49.55
  linux-image-5.8.0-49-lowlatency  5.8.0-49.55
  linux-image-aws                 5.8.0.1028.30
  linux-image-azure               5.8.0.1027.27
  linux-image-gcp                 5.8.0.1027.27
  linux-image-generic             5.8.0.49.54
  linux-image-generic-64k         5.8.0.49.54
  linux-image-generic-lpae        5.8.0.49.54
  linux-image-gke                 5.8.0.1027.27
  linux-image-kvm                 5.8.0.1023.25
  linux-image-lowlatency          5.8.0.49.54
  linux-image-oem-20.04           5.8.0.49.54
  linux-image-oracle              5.8.0.1025.24
  linux-image-raspi               5.8.0.1020.23
  linux-image-raspi-nolpae        5.8.0.1020.23
  linux-image-virtual             5.8.0.49.54

Ubuntu 20.04 LTS:
  linux-image-5.8.0-49-generic    5.8.0-49.55~20.04.1
  linux-image-5.8.0-49-generic-64k  5.8.0-49.55~20.04.1
  linux-image-5.8.0-49-generic-lpae  5.8.0-49.55~20.04.1
  linux-image-5.8.0-49-lowlatency  5.8.0-49.55~20.04.1
  linux-image-generic-64k-hwe-20.04  5.8.0.49.55~20.04.33
  linux-image-generic-hwe-20.04   5.8.0.49.55~20.04.33
  linux-image-generic-lpae-hwe-20.04  5.8.0.49.55~20.04.33
  linux-image-lowlatency-hwe-20.04  5.8.0.49.55~20.04.33
  linux-image-virtual-hwe-20.04   5.8.0.49.55~20.04.33

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.