RUSTSEC-2020-0124: async-coap: ArcGuard's Send and Sync should have bounds on RC

Description

Affected versions of this crate implement Send/Sync for ArcGuard<RC, T> with no trait bounds on RC. This allows users to send RC: !Send to other threads and also allows users to concurrently access Rc: !Sync from multiple threads.

This can result in memory corruption from data race or other undefined behavior caused by sending T: !Send to other threads (e.g. dropping MutexGuard<T> in another thread that didn’t lock its mutex).

More Info

https://github.com/google/rust-async-coap/issues/33

Patched Versions