HistoryEdit

RUSTSEC-2022-0078

Use-after-free due to a lifetime error in Vec::into_iter()

Reported
Issued
Package
bumpalo (crates.io)
Type
INFO Unsound
Categories
Keywords
#use-after-free
Details
https://github.com/fitzgen/bumpalo/blob/main/CHANGELOG.md#3111
Patched
  • >=3.11.1
Unaffected
  • <1.1.0
Affected Functions
Version
bumpalo::collections::vec::Vec::into_iter
  • <3.11.1

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(&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.