Random MariaDB Buffer Overflows

We've had a couple of these in the past, can't seem to find any pattern or cause to them so I'm now seeking help. Attached is the syslog entries (cut after MariaDB goes into recovery) from today's crash - hoping someone can help dial in what the issue is. It's a reasonable sized server with about 10k databases totalling about 450GB in files, so the restarts after these take a few hours.