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this post was submitted on 21 Feb 2024
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Programming
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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.