Interesting. I've been eyeing OS development for a while myself. I have a few high-level ideas about kernel design, and a few years's worth of musings about good UX. I badly need to get on with spending a few years getting my feet wet with actual implementation details and such so I'm not just a pile of unorientated hot air though, haha. Armchair pontificating doesn't count for much. But anyway.
Huh, a shell and Vim. (Alongside multiple architecture support and two filesystems.) That's reasonably developed-out. Not bad!
Can totally understand the problem of running out of steam. (I think that might be why I've been so hesitant about diving in myself - want to pace things so they stay interesting for long enough, and don't want to make too many discouraging mistakes. A couple kernel architecture arguments doesn't produce a good filesystem, adequately future-proof UI model, good vertical "little detail" semantics, etc etc.
A hard crash on multiple platforms? That's almost definitely a bug. Heh, I think all the downvoters might've made a bunch of incorrect presumptions there :)
It might be mildly interesting to see if you can still trigger the crash with the latest version of VirtualBox. (I'd have a go but of course I have no repro details, or info on how to actually build everything for that matter.)
Precedent has just been set on 0daying VB networking hardware, for what that's worth :P but there's also Project Zero (which will accept security vulnerabilities in any software, and imposes a 90-day deadline) if VB's own bug bounty thing proves unappealing. This is of course getting a bit ahead of testing/re-verification. I mention it because I'm now very curious to know if the bug is still there, but of course HN comments are not the right place for a [Y] :)
It's impossible to say if recreating the test environment (host OS version(s), host VirtualBox version) would prove fruitful if the latest VB versions seem (...seem...) immune. Vulnerability research seems to be consist of a lot of "hmm, that seems like it might run a tiny bit slower on months with a Q in them if the computer is leaning 30° to the left at 2:14PM in the afternoon" and then staring at Hex-Rays for 3 months to ultimately prove that your crazy theory is in fact valid (literal example https://ramtin-amin.fr/#nvmedma; very similar example https://bugs.chromium.org/p/chromium/issues/detail?id=648971 - "one byte overflow"!).
In any case, I wouldn't mind getting some more details and seeing the CLUNK in action. It's interesting at face value.
NB. About that nvmedma link - it took me about 4-5 rereads of that article and its prequel (https://ramtin-amin.fr/#nvmepcie) before the bigger picture started to click.
(I also need to check my comments somewhat frequently - and then remember to also actually follow-up after seeing I have replies! Woops. Thanks for the reply!)