[USN-4911-1] Linux kernel (OEM) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-4911-1
April 13, 2021

linux-oem-5.10 vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-oem-5.10: Linux kernel for OEM systems

Details:

It was discovered that the Nouveau GPU driver in the Linux kernel did not
properly handle error conditions in some situations. A local attacker could
use this to cause a denial of service (system crash). (CVE-2020-25639)

Jan Beulich discovered that the Xen netback backend in the Linux kernel did
not properly handle certain error conditions under paravirtualization. An
attacker in a guest VM could possibly use this to cause a denial of service
(host domain crash). (CVE-2021-28038)

It was discovered that the fastrpc driver in the Linux kernel did not
prevent user space applications from sending kernel RPC messages. A local
attacker could possibly use this to gain elevated privileges.
(CVE-2021-28375)

It was discovered that the fuse user space file system implementation in
the Linux kernel did not properly handle bad inodes in some situations. A
local attacker could possibly use this to cause a denial of service.
(CVE-2021-28950)

Update instructions:

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

Ubuntu 20.04 LTS:
  linux-image-5.10.0-1021-oem     5.10.0-1021.22
  linux-image-oem-20.04b          5.10.0.1021.22

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-4911-1
  CVE-2020-25639, CVE-2021-28038, CVE-2021-28375, CVE-2021-28950

Package Information:
  https://launchpad.net/ubuntu/+source/linux-oem-5.10/5.10.0-1021.22

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