I’ve been fuzz-testing libopenmpt for a while now, and just for the sake of it I threw some of the test cases that crashed libopenmpt at Renoise as well - and lo and behold, some of them crash Renoise as well.
I’ve attached three IT files that make Renoise crash either when loading or playing the file. Please disregard the filenames, those are just indications of what went wrong in libopenmpt.
If you are interested, I have a test corpus of more than 50,000 files generated with American Fuzzy Lop. Many of those files won’t even load in Renoise because it doesn’t support those formats, but others will definitely load and maybe provoke further crashes. Maybe you can find a way to automatically feed all those files into Renoise for stress-testing it.