Linux Kernel EUVD-2026-27709

In the Linux kernel, the following vulnerability has been resolved:

perf/arm-cmn: Reject unsupported hardware configurations

So far we've been fairly lax about accepting both unknown CMN models (at least with a warning), and unknown revisions of those which we do know, as although things do frequently change between releases, typically enough remains the same to be somewhat useful for at least some basic bringup checks. However, we also make assumptions of the maximum supported sizes and numbers of things in various places, and there's no guarantee that something new might not be bigger and lead to nasty array overflows. Make sure we only try to run on things that actually match our assumptions and so will not risk memory corruption.

We have at least always failed on completely unknown node types, so update that error message for clarity and consistency too.