GHSA-qc84-gqf4-9926

crossbeam-utils Unsoundness of AtomicCell<{i,u}64> arithmetics on 32-bit targets that support Atomic{I,U}64

### Impact The affected versions of this crate incorrectly assumed that the alignment of `{i,u}64` was always the same as `Atomic{I,U}64`. However, the alignment of `{i,u}64` on a 32-bit target can be smaller than `Atomic{I,U}64`. This can cause the following problems: - Unaligned memory accesses - Data race Crates using `fetch_*` methods with `AtomicCell<{i,u}64>` are affected by this issue. 32-bit targets without `Atomic{I,U}64` and 64-bit targets are not affected by this issue. 32-bit targets with `Atomic{I,U}64` and `{i,u}64` have the same alignment are also not affected by this issue. The following is a complete list of the builtin targets that may be affected. (last update: nightly-2022-02-11) - armv7-apple-ios (tier 3) - armv7s-apple-ios (tier 3) - i386-apple-ios (tier 3) - i586-unknown-linux-gnu - i586-unknown-linux-musl - i686-apple-darwin (tier 3) - i686-linux-android - i686-unknown-freebsd - i686-unknown-haiku (tier 3) - i686-unknown-linux-gnu - i686-unknown-linux-musl - i686-unknown-netbsd (tier 3) - i686-unknown-openbsd (tier 3) - i686-wrs-vxworks (tier 3) ([script to get list](https://gist.github.com/taiki-e/3c7891e8c5f5e0cbcb44d7396aabfe10)) ### Patches This has been fixed in crossbeam-utils 0.8.7. Affected 0.8.x releases have been yanked. ### References https://github.com/crossbeam-rs/crossbeam/pull/781 ### License This advisory is in the public domain.