Crossbeam is a set of tools for concurrent programming. In crossbeam-channel before version 0.4.4, the bounded channel incorrectly assumes that Vec::fromiter has allocated capacity that same as the number of iterator elements. Vec::fromiter does not actually guarantee that and may allocate extra memory. The destructor of the bounded channel reconstructs Vec from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when Vec::fromiter has allocated different sizes with the number of iterator elements. This has been fixed in crossbeam-channel 0.4.4.

crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in Rust. In versions prior to 0.7.4 and 0.8.0, the result of the race condition is that one or more tasks in the worker queue can be popped twice instead of other tasks that are forgotten and never popped. If tasks are allocated on the heap, this can cause double free and a memory leak. If not, this still can cause a logical bug. Crates using Stealer::steal, Stealer::stealbatch, or Stealer::stealbatchandpop are affected by this issue. This has been fixed in crossbeam-deque 0.8.1 and 0.7.4.

An issue was discovered in the crossbeam crate before 0.4.1 for Rust. There is a double free because of destructor mishandling.

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.