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Ubuntu Security Notice USN-6648-2
February 28, 2024

linux-azure, linux-azure-5.4 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS (Available with Ubuntu Pro)

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-azure-5.4: Linux kernel for Microsoft Azure cloud systems

Details:

It was discovered that a race condition existed in the AppleTalk networking
subsystem of 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-2023-51781)

Zhenghan Wang discovered that the generic ID allocator implementation in
the Linux kernel did not properly check for null bitmap when releasing IDs.
A local attacker could use this to cause a denial of service (system
crash). (CVE-2023-6915)

Robert Morris discovered that the CIFS network file system implementation
in the Linux kernel did not properly validate certain server commands
fields, leading to an out-of-bounds read vulnerability. An attacker could
use this to cause a denial of service (system crash) or possibly expose
sensitive information. (CVE-2024-0565)

Jann Horn discovered that the TLS subsystem in the Linux kernel did not
properly handle spliced messages, leading to an out-of-bounds write
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly execute arbitrary code. (CVE-2024-0646)

Update instructions:

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

Ubuntu 20.04 LTS:
   linux-image-5.4.0-1124-azure    5.4.0-1124.131
   linux-image-azure-lts-20.04     5.4.0.1124.117

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
   linux-image-5.4.0-1124-azure    5.4.0-1124.131~18.04.1
   linux-image-azure               5.4.0.1124.97

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-6648-2
   https://ubuntu.com/security/notices/USN-6648-1
   CVE-2023-51781, CVE-2023-6915, CVE-2024-0565, CVE-2024-0646

Package Information:
   https://launchpad.net/ubuntu/+source/linux-azure/5.4.0-1124.131