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

Not scored Published 14 Jan 2022

A lifetime error in bumpalo's Vec::into_iter allows use-after-free, potentially leading to memory corruption or crashes when the allocator is dropped.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Not stated
Victim action needed: Not needed
Fix: Available

What is GHSA-f85w-wvc7-crwc?

GHSA-f85w-wvc7-crwc is an use after free vulnerability in bumpalo, published on 14 Jan 2022.

Official description

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(&amp;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!(&#34;0x{:02x} &#34;, 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.

Which versions are affected by GHSA-f85w-wvc7-crwc?

3 open source packages ship an affected version, including bumpalo.

Package	Affected	Fixed in
`bumpalo` crates.io	From `1.1.0`	`3.11.1`
`bumpalo` crates.io	From `1.1.0`	`3.11.1`
`bumpalo` crates.io	From `1.1.0`	`3.11.1`

How do I fix GHSA-f85w-wvc7-crwc?

Upgrade bumpalo to 3.11.1 or later.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is GHSA-f85w-wvc7-crwc being exploited?

There is no known exploitation of GHSA-f85w-wvc7-crwc in the wild and no public exploit code.

Sources

Also known as RUSTSEC-2022-0078.