miniblog.

Wilfred Hughes

Dec 4, 2019 at 07:15

An unsoundness in Rust using only safe code! Rust provides a bunch of guarantees so it's always interesting to see the rare ways it can be broken. I think this is the first unsoundness since the thread spawn issue after 1.0? https://internals.rust-lang.org/t/unsoundness-in-pin/11311

Unsoundness in `Pin`

Recently, @withoutboats challenged me to demonstrate a hypothetical version of Pin with different guarantees, and show how it would be sound. However, while working on that, I stumbled upon unsoundness in the actual Pin. I haven't seen this reported before, though I could have missed it. Playground link: proof of concept (methods 1 and 2) This code demonstrates two related exploits to obtain a Pin<&mut T> from &mut T, ultimately resulting in a segfault. It compiles on stable and has no unsa...