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)

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.