this post was submitted on 21 Feb 2024
155 points (97.5% liked)
Programming
17270 readers
39 users here now
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
- Follow the programming.dev instance rules
- Keep content related to programming in some way
- If you're posting long videos try to add in some form of tldr for those who don't want to watch videos
Wormhole
Follow the wormhole through a path of communities [email protected]
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
It's utilizing an obscure bug in the Rust compiler that unfortunately lets you circumvent the safety guarantees in order to produce undefined behavior - it's mostly just a joke though, you will not run into the bug in normal code
Thanks for clarifying. Do you know what the bug is? I gathering it's something to do with enums and boxing to enable a "safe" transmute, but couldn't make sense of the code.
Scary compiler edge cases with value-type enums aren't surprising though. Trying to implement that feature with memory safety and high performance sounds like a nightmare.
It's essentially this issue https://github.com/rust-lang/rust/issues/25860
The code used to exploit the bug in this library is here: https://github.com/Speykious/cve-rs/blob/main/src/lifetime_expansion.rs
As far as I understand, the bug basically makes it so you can trick Rust into thinking any lifetime is actually 'static. From that, you can do all kinds of bad stuff.