This was first discovered when trying to watch TV on my MythTV box. The screen went black for a few moments, and then returned to the menu.
Digging for the cause, I found my way to the mariadb log, which explained the server had got a segmentation violation. I attach a log where I first restart the Mariadb server, then go over to the MythTV machine (not the same box) and select "watch TV". As you can see, it explains it gets signal 11, and then produce a lot of information I hope can help understand what the issue is.
In that log, there is a SELECT statement. The crash always happens on the same statement. I have tried to run the same statement using the mysql command line tool. I am not able to trigger the problem that way, even after doing a cut-and-paste of the query, even including all the spaces verbatim.
I also attach the core file produced. (I've been trying to look a little myself, and can see the cause is a null pointer being used, created as sa in Type_handler_string_result::Item_const_eq. But I would need much more understanding why this call produces a null pointer.)
The mysqld binary is the standard binary from the Fedora distribution, but for convenience I attach that too.