Current status of Spectre/Meltdown on Ubuntu 17.10
Linux Chef/Author Marcel Gagne posted a link to a Spectre/Meltdown tool recently on Twitter: https://twitter.com/wftl/status/954004068292165632. I tested one of the systems I use and despite the fact that it's running the latest (but not bleeding edge) Ubuntu 17.10 the kernel appears to venerable to at least 2 of the 3 vulnerabilities (both Spectre-related). I looked around for how to patch the kernel, found one site in particular with the words "patch," "Ubuntu 17.10" and "Spectre/Meltdown," but after completing all the steps it didn't resolve the two Spectre issues. At first I thought I might have skipped a step (in truth I did all the steps long before the article, but I redid the steps anyway) and then I noticed near the bottom of the article that Canonical apparently hasn't resolved the two issues yet.
I also tried upgrading to a more bleeding edge kernel, but I ended up with an un-bootable system, so I reverted back to the old (4.13.0-25-generic) kernel.
Softpedia had an article that indicated some patches were made to Firefox version 57.0.4 to help mitigate the Spectre problem. The system I ran the spectre checker on happens to run Firefox 57.0.4. So, although the kernel is still susceptible to attack, Firefox is at least helping mitigate the attacks until a more complete solution can be found.
During the process I also talked with one of our volunteers in Computer Recycling who mentioned that the Linux Mint web site has quite good information about Spectre/Meltdown as they relate to Mint. The Linux Mint team appears to have already patched the issue in the kernel, and they've also outlined Firefox, Chrome, Opera, and NVidia patches.