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USN-4748-1: Linux kernel vulnerabilities

25 February 2021

Several security issues were fixed in the Linux kernel.

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Releases

Packages

Details

It was discovered that the jfs file system implementation in the Linux
kernel contained an out-of-bounds read vulnerability. A local attacker
could use this to possibly cause a denial of service (system crash).
(CVE-2020-27815)

It was discovered that the memory management subsystem in the Linux kernel
did not properly handle copy-on-write operations in some situations. A
local attacker could possibly use this to gain unintended write access to
read-only memory pages. (CVE-2020-29374)

Michael Kurth and Pawel Wieczorkiewicz discovered that the Xen event
processing backend in the Linux kernel did not properly limit the number of
events queued. An attacker in a guest VM could use this to cause a denial
of service in the host OS. (CVE-2020-29568)

Jann Horn discovered that the tty subsystem of the Linux kernel did not use
consistent locking in some situations, leading to a read-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly expose sensitive information (kernel memory).
(CVE-2020-29660)

Jann Horn discovered a race condition in the tty subsystem of the Linux
kernel in the locking for the TIOCSPGRP ioctl(), 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-2020-29661)

Reduce your security exposure

Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

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Update instructions

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

Ubuntu 16.04
Ubuntu 14.04

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

Related notices

  • USN-4749-1: linux-aws-hwe, linux-image-lowlatency-hwe-16.04-edge, linux-image-4.15.0-1093-gcp, linux-image-gke, linux-image-4.15.0-1065-oracle, linux-image-4.15.0-1012-dell300x, linux-azure, linux-image-snapdragon, linux-image-generic-hwe-16.04-edge, linux-image-virtual-hwe-16.04-edge, linux-image-4.15.0-1085-kvm, linux-image-4.15.0-136-generic, linux-image-raspi2, linux-gcp-4.15, linux-image-4.15.0-136-lowlatency, linux-snapdragon, linux-image-generic-lpae-hwe-16.04, linux-aws, linux-image-gcp-lts-18.04, linux-image-generic, linux-image-oracle, linux-hwe, linux-image-oem, linux-image-gcp, linux-gcp, linux, linux-oracle, linux-image-4.15.0-1094-aws, linux-raspi2, linux-image-4.15.0-1108-azure, linux-image-4.15.0-1079-gke, linux-image-4.15.0-136-generic-lpae, linux-gke-4.15, linux-image-azure-edge, linux-image-dell300x, linux-image-generic-lpae-hwe-16.04-edge, linux-image-4.15.0-1096-snapdragon, linux-image-azure, linux-azure-4.15, linux-image-kvm, linux-image-oracle-lts-18.04, linux-image-generic-hwe-16.04, linux-image-virtual-hwe-16.04, linux-image-azure-lts-18.04, linux-image-4.15.0-1079-raspi2, linux-image-gke-4.15, linux-image-lowlatency, linux-image-aws-lts-18.04, linux-image-lowlatency-hwe-16.04, linux-image-virtual, linux-dell300x, linux-image-aws-hwe, linux-image-generic-lpae, linux-kvm
  • USN-4750-1: linux-image-5.4.0-1038-aws, linux-image-generic-hwe-18.04-edge, linux-image-5.4.0-1037-gcp, linux-oracle-5.4, linux-image-raspi-hwe-18.04-edge, linux-image-5.4.0-66-generic-lpae, linux-image-5.4.0-66-generic, linux-azure, linux-azure-5.4, linux-image-snapdragon-hwe-18.04-edge, linux-image-5.4.0-1033-kvm, linux-gkeop-5.4, linux-gke-5.4, linux-image-generic-lpae, linux-image-raspi, linux-image-aws-edge, linux-image-snapdragon-hwe-18.04, linux-image-5.4.0-66-lowlatency, linux-image-5.4.0-1040-azure, linux-image-generic-hwe-18.04, linux-image-lowlatency-hwe-18.04-edge, linux-image-oem-osp1, linux-image-raspi2, linux-image-lowlatency-hwe-18.04, linux-gkeop, linux-raspi, linux-aws, linux-image-generic, linux-image-raspi2-hwe-18.04-edge, linux-image-virtual-hwe-18.04-edge, linux-image-gke-5.4, linux-image-oem, linux-image-aws, linux-image-gcp, linux-gcp, linux-image-5.4.0-1029-raspi, linux, linux-image-virtual-hwe-18.04, linux-oracle, linux-raspi-5.4, linux-image-5.4.0-1038-oracle, linux-image-oracle-edge, linux-image-gkeop, linux-image-5.4.0-1010-gkeop, linux-image-5.4.0-1036-gke, linux-image-azure-edge, linux-gcp-5.4, linux-image-azure, linux-image-kvm, linux-aws-5.4, linux-image-gkeop-5.4, linux-image-raspi-hwe-18.04, linux-image-raspi2-hwe-18.04, linux-hwe-5.4, linux-image-generic-lpae-hwe-18.04-edge, linux-image-generic-lpae-hwe-18.04, linux-image-lowlatency, linux-image-virtual, linux-image-oracle, linux-image-gcp-edge, linux-kvm
  • USN-4751-1: linux-image-generic-lpae-hwe-20.04-edge, linux-image-gke, linux-image-generic-lpae-hwe-20.04, linux-image-generic-64k-hwe-20.04-edge, linux-azure, linux-image-lowlatency-hwe-20.04, linux-image-raspi, linux-image-5.8.0-1021-oracle, linux-image-5.8.0-1023-gcp, linux-image-5.8.0-44-generic-64k, linux-image-5.8.0-1016-raspi, linux-raspi, linux-image-5.8.0-44-generic-lpae, linux-aws, linux-image-5.8.0-44-generic, linux-image-generic, linux-image-oem-20.04, linux-image-aws, linux-image-gcp, linux-gcp, linux, linux-oracle, linux-image-virtual-hwe-20.04-edge, linux-image-kvm, linux-image-azure, linux-kvm, linux-image-generic-hwe-20.04, linux-image-generic-64k-hwe-20.04, linux-image-5.8.0-1023-azure, linux-image-5.8.0-44-lowlatency, linux-image-5.8.0-1016-raspi-nolpae, linux-image-raspi-nolpae, linux-hwe-5.8, linux-image-generic-hwe-20.04-edge, linux-image-generic-64k, linux-image-virtual-hwe-20.04, linux-image-lowlatency, linux-image-virtual, linux-image-oracle, linux-image-generic-lpae, linux-image-lowlatency-hwe-20.04-edge, linux-image-5.8.0-1019-kvm, linux-image-5.8.0-1024-aws
  • USN-4752-1: linux-image-oem-20.04, linux-image-5.6.0-1048-oem, linux-oem-5.6
  • USN-5130-1: linux-headers-generic-lts-trusty, linux-buildinfo-3.13.0-188-powerpc-e500mc, linux-virtual, linux-source-3.13.0, linux-image-server, linux-modules-3.13.0-188-powerpc-e500mc, linux-tools-generic-lpae, linux-hwe-virtual-trusty, linux-image-generic-lts-trusty, linux-libc-dev, linux-image-highbank, linux-headers-powerpc64-emb, linux-hwe-generic-trusty, linux-image-generic, linux-cloud-tools-virtual, linux-tools-powerpc-smp, linux-cloud-tools-common, linux-generic-pae, linux-buildinfo-3.13.0-188-lowlatency, linux-headers-powerpc-smp, linux, linux-image-powerpc-smp, linux-tools-3.13.0-188-powerpc-e500mc, linux-image-hwe-generic-trusty, linux-cloud-tools-lowlatency, linux-generic-lpae-lts-saucy-eol-upgrade, linux-headers-powerpc64-smp, linux-image-3.13.0-188-powerpc64-smp, linux-buildinfo-3.13.0-188-powerpc64-smp, linux-image-extra-virtual, linux-image-generic-pae, linux-image-lowlatency-pae, linux-powerpc-smp, linux-buildinfo-3.13.0-188-generic-lpae, linux-generic-lpae-lts-saucy, linux-tools-3.13.0-188-lowlatency, linux-tools-lowlatency, linux-headers-powerpc-e500, linux-modules-3.13.0-188-powerpc-e500, linux-cloud-tools-3.13.0-188-generic, linux-tools-generic-lpae-lts-saucy, linux-image-virtual, linux-tools-lts-trusty, linux-tools-generic-lts-trusty, linux-lowlatency-pae, linux-image-unsigned-3.13.0-188-generic, linux-image-generic-lpae, linux-tools-powerpc64-smp, linux-headers-highbank, hv-kvp-daemon-init, linux-buildinfo-3.13.0-188-powerpc64-emb, linux-image-generic-lts-saucy, linux-signed-generic-lts-trusty, linux-tools-lts-saucy, linux-tools-3.13.0-188, linux-generic-lts-saucy-eol-upgrade, linux-image-3.13.0-188-powerpc-e500mc, linux-image-3.13.0-188-lowlatency, linux-crashdump, linux-signed-generic-lts-saucy, linux-server, linux-buildinfo-3.13.0-188-powerpc-e500, linux-modules-3.13.0-188-powerpc-smp, linux-powerpc64-smp, linux-generic-lts-saucy, linux-headers-virtual, linux-generic-lts-raring-eol-upgrade, linux-signed-image-generic-lts-quantal, linux-headers-generic-lpae-lts-saucy, linux-powerpc64-emb, linux-tools-powerpc64-emb, linux-headers-3.13.0-188-powerpc64-smp, linux-headers-lowlatency-pae, linux-signed-generic-lts-raring-eol-upgrade, linux-generic-lts-raring, linux-headers-3.13.0-188-powerpc-e500, linux-tools-3.13.0-188-generic-lpae, linux-doc, linux-tools-3.13.0-188-powerpc64-smp, linux-image-powerpc-e500, linux-generic-lpae, linux-headers-3.13.0-188-powerpc64-emb, linux-buildinfo-3.13.0-188-powerpc-smp, linux-generic-lts-trusty, linux-powerpc-e500, linux-headers-generic-pae, linux-headers-omap, linux-modules-extra-3.13.0-188-generic, linux-lowlatency, linux-image-powerpc64-smp, linux-headers-generic-lpae-lts-trusty, linux-image-omap, linux-cloud-tools-3.13.0-188-lowlatency, linux-tools-common, linux-image-lowlatency, linux-tools-3.13.0-188-powerpc-e500, linux-headers-3.13.0-188, linux-tools-3.13.0-188-powerpc-smp, linux-image-generic-lts-quantal, linux-signed-generic-lts-quantal, linux-modules-3.13.0-188-powerpc64-emb, linux-generic, linux-image-hwe-virtual-trusty, linux-tools-powerpc-e500mc, linux-image-3.13.0-188-powerpc64-emb, linux-headers-generic, linux-modules-3.13.0-188-lowlatency, linux-headers-3.13.0-188-generic, linux-tools-3.13.0-188-powerpc64-emb, linux-image-generic-lpae-lts-saucy, linux-headers-generic-lts-quantal, linux-headers-generic-lts-saucy, linux-signed-generic-lts-quantal-eol-upgrade, linux-headers-lowlatency, linux-tools-generic-lpae-lts-trusty, linux-signed-generic, linux-generic-lpae-lts-trusty, linux-signed-image-generic-lts-trusty, linux-cloud-tools-generic, linux-headers-3.13.0-188-lowlatency, linux-image-3.13.0-188-generic, linux-highbank, linux-headers-3.13.0-188-powerpc-smp, linux-headers-powerpc-e500mc, linux-image-3.13.0-188-powerpc-smp, linux-image-unsigned-3.13.0-188-lowlatency, linux-image-powerpc64-emb, linux-signed-image-generic, linux-modules-3.13.0-188-generic, linux-omap, linux-image-generic-lpae-lts-trusty, linux-tools-virtual, linux-powerpc-e500mc, linux-headers-3.13.0-188-generic-lpae, linux-cloud-tools-3.13.0-188, linux-headers-3.13.0-188-powerpc-e500mc, linux-image-3.13.0-188-generic-lpae, linux-modules-3.13.0-188-generic-lpae, linux-buildinfo-3.13.0-188-generic, linux-modules-3.13.0-188-powerpc64-smp, linux-tools-powerpc-e500, linux-headers-generic-lts-raring, linux-headers-server, linux-image-3.13.0-188-powerpc-e500, linux-signed-image-generic-lts-saucy, linux-signed-generic-lts-saucy-eol-upgrade, linux-source, linux-tools-generic-lts-saucy, linux-image-generic-lts-raring, linux-image-powerpc-e500mc, linux-signed-image-generic-lts-raring, linux-tools-generic, linux-headers-generic-lpae, linux-tools-3.13.0-188-generic, linux-signed-generic-lts-raring, linux-generic-lts-quantal-eol-upgrade, linux-generic-lts-quantal, linux-tools-lts-quantal, linux-tools-lts-raring
  • LSN-0082-1: gkeop-5.4, generic-4.15, gcp, gke, generic-5.4, gkeop, lowlatency-4.4, lowlatency-4.15, oem, lowlatency-5.4, gke-5.4, gke-4.15, generic-4.4

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