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Ubuntu Security Notice USN-4884-1
March 20, 2021

linux-oem-5.10 vulnerabilities
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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:

Loris Reiff discovered that the BPF implementation in the Linux kernel did
not properly validate attributes in the getsockopt BPF hook. A local
attacker could possibly use this to cause a denial of service (system
crash). (CVE-2021-20194)

It was discovered that the priority inheritance futex implementation in the
Linux kernel contained a race condition, 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-2021-3347)

It was discovered that the network block device (nbd) driver in the Linux
kernel contained a use-after-free vulnerability during device setup. A
local attacker with access to the nbd device could use this to cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2021-3348)

Update instructions:

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

Ubuntu 20.04 LTS:
  linux-image-5.10.0-1017-oem     5.10.0-1017.18
  linux-image-oem-20.04b          5.10.0.1017.18

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-4884-1
  CVE-2021-20194, CVE-2021-3347, CVE-2021-3348

Package Information:
  https://launchpad.net/ubuntu/+source/linux-oem-5.10/5.10.0-1017.18