Smart Pointers Can't Solve Use-After-Free in C++

The way that expert programmers make these same mistakes is by introducing a few layers of abstraction. Here's a real CVE from Microsoft: https://msrc.microsoft.com/blog/2019/07/we-need-a-safer-syst...

> This bug is possible because of how many complex APIs interact with each other and the programmer not being able to enforce ownership of memory throughout the codebase. At [0], the program gets a pointer to a buffer owned by a JavaScript object. Then at [1], because of the language complexity, to get another variable, it might execute more JavaScript code. At [2], it will use the buffer and width to create a new JavaScript object with the contents of that pointer.

So to adapt that example, the way an expert programmer in a complicated codebase might end up invalidating an iterator, could be by looping over a list that user-provided scripts are allowed to modify, and then accidentally re-entering script code in that loop. It might take a really contrived script to exploit the bug, but such is life in the browser/JS world.