=========================================================================Ubuntu Security Notice USN-6051-1
May 01, 2023

linux-azure-5.15, linux-azure-fde, linux-kvm vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-azure-fde: Linux kernel for Microsoft Azure CVM cloud systems
- linux-kvm: Linux kernel for cloud environments
- linux-azure-5.15: Linux kernel for Microsoft Azure cloud systems

Details:

It was discovered that the Traffic-Control Index (TCINDEX) implementation
in the Linux kernel did not properly perform filter deactivation in some
situations. A local attacker could possibly use this to gain elevated
privileges. Please note that with the fix for this CVE, kernel support for
the TCINDEX classifier has been removed. (CVE-2023-1829)

It was discovered that a race condition existed in the io_uring subsystem
in the Linux kernel, 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-2023-1872)

Update instructions:

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

Ubuntu 22.04 LTS:
   linux-image-5.15.0-1032-kvm     5.15.0-1032.37
   linux-image-5.15.0-1037-azure-fde  5.15.0-1037.44.1
   linux-image-azure-fde           5.15.0.1037.44.14
   linux-image-kvm                 5.15.0.1032.28

Ubuntu 20.04 LTS:
   linux-image-5.15.0-1037-azure   5.15.0-1037.44~20.04.1
   linux-image-azure               5.15.0.1037.44~20.04.27
   linux-image-azure-cvm           5.15.0.1037.44~20.04.27

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:
   
   CVE-2023-1829, CVE-2023-1872

Package Information:
   https://launchpad.net/ubuntu/+source/linux-azure-fde/5.15.0-1037.44.1
   https://launchpad.net/ubuntu/+source/linux-kvm/5.15.0-1032.37
   https://launchpad.net/ubuntu/+source/linux-azure-5.15/5.15.0-1037.44~20.04.1