Aha! I think I understand what has you confused. You seem to think that the TLDR describes some basic rule of XNU programming that people were already aware of and expected to follow. No. Ian Beer invented that rule. In this post. That's why the bug is such a big deal; it's why we call it a "new bug class". It's also why it's the TLDR of the post.
Wow straight up conclusion - I had it confused, right!
It's not a, pardon me for the expression, fucking XNU specific programming rule - it is a general rule that was invented long before Ian got to it! You don't hold a reference counted pointer and operate on it without taking a :gasp: reference first - having that shit in your sample code is just, well extra shitty!
Also, separately from the dangling pointer issue, the first sentence of the post is literally - This post discusses a design issue at the core of the XNU kernel!
