How-Tos

How-To: Make Sure Your Ubuntu Box Isn’t Missing Old Kernel Fixes

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The GNU Savannah story had a sting in the tail: the server ran a 5.15 kernel still open to 2023’s GameOver(lay) bugs. Here’s a quick check for your own Ubuntu-based machines.

1. What are you running vs. what’s installed?

uname -r                                   # running kernel
dpkg -l 'linux-image-*' | awk '/^ii/{print $2,$3}'   # installed kernels
apt list --upgradable 2>/dev/null | grep -i linux

2. Did you install a fix but never reboot?

[ -f /var/run/reboot-required ] && cat /var/run/reboot-required.pkgs
sudo needrestart -k    # if needrestart is installed

3. Ask about a specific CVE

pro fix CVE-2023-2640
pro fix CVE-2023-32629
pro security-status

pro fix tells you whether you’re affected and what package fixes it. It’s part of the Ubuntu Pro client, and the basic checks work without a paid subscription.

4. Keep it from happening again

  • Turn on unattended-upgrades for security updates.
  • Put kernel reboots on a calendar. A patched kernel that’s never booted is still unpatched.
  • If you manage several boxes, put this in your config management (I use Ansible) instead of doing it by hand.

Review before you run anything: read the docs yourself, back up your config, and try it somewhere you can afford to break first.

God Bless, and Happy hacking!

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