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Ubuntu 20.04 LTS USN-4367-2: Critical Kernel Regression Fix

ubuntu
Calendar Grey May 28, 2020
Dist Ubuntu Esm H88
Uncover the kernel flaws in Ubuntu 20.04 LTS following USN-4367-1, which caused significant problems, and learn how these obstacles were addressed successfully.
USN-4367-1 introduced a regression in the Linux kernel.

Summary

USN-4367-1 introduced a regression in the Linux kernel.

Software Description:

- linux: Linux kernel

Details:

USN-4367-1 fixed vulnerabilities in the 5.4 Linux kernel. Unfortunately,

that update introduced a regression in overlayfs. This update corrects

the problem.

We apologize for the inconvenience.

Original advisory details:

It was discovered that the btrfs implementation in the Linux kernel did not

properly detect that a block was marked dirty in some situations. An

attacker could use this to specially craft a file system image that, when

unmounted, could cause a denial of service (system crash). (CVE-2019-19377)

It was discovered that the linux kernel did not properly validate certain

mount options to the tmpfs virtual memory file system. A local attacker

with the ability to specify mount options could use this to cause a denial

of service (system crash). (CVE-2020-11565)

It was discovered that the block layer in the Linux kernel contained a race

condition lea...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory DoS Ubuntu system crash kernel regression overlayfs issue

Update Instructions

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

Ubuntu 20.04 LTS:
  linux-image-5.4.0-33-generic    5.4.0-33.37
  linux-image-5.4.0-33-generic-lpae  5.4.0-33.37
  linux-image-5.4.0-33-lowlatency  5.4.0-33.37
  linux-image-generic             5.4.0.33.38
  linux-image-generic-lpae        5.4.0.33.38
  linux-image-lowlatency          5.4.0.33.38
  linux-image-oem                 5.4.0.33.38
  linux-image-oem-osp1            5.4.0.33.38
  linux-image-virtual             5.4.0.33.38

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://ubuntu.com/security/notices/USN-4367-2

https://ubuntu.com/security/notices/USN-4367-1

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1879690

Severity
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May 28, 2020

Topics%20covered

Topics Covered

security advisory DoS Ubuntu system crash kernel regression overlayfs issue

Package Information

https://launchpad.net/ubuntu/+source/linux/5.4.0-33.37

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