GHSA-f85w-wvc7-crwc: bumpalo has use-after-free due to a lifetime error in `Vec::into_iter()`

In affected versions of this crate, the lifetime of the iterator produced by Vec::into_iter() is not constrained to the lifetime of the Bump that allocated the vector’s memory. Using the iterator after the Bump is dropped causes use-after-free accesses.

The following example demonstrates memory corruption arising from a misuse of this unsoundness.

use bumpalo::{collections::Vec, Bump};

fn main() {
let bump = Bump::new();
let mut vec = Vec::new_in(&bump);
vec.extend([0x01u8; 32]);
let into_iter = vec.into_iter();
drop(bump);

for _ in 0..100 {
let reuse_bump = Bump::new();
let _reuse_alloc = reuse_bump.alloc([0x41u8; 10]);
}

for x in into_iter {
print!("0x{:02x} ", x);
}
println!();
}

The issue was corrected in version 3.11.1 by adding a lifetime to the IntoIter type, and updating the signature of Vec::into_iter() to constrain this lifetime.