Spin is no longer actively maintained (RUSTSEC-2019-0031)

[gendx]

Running cargo audit on https://github.com/google/OpenSK reveals that linked_list_allocator depends on spin, which is no longer actively maintained (advisory RUSTSEC-2019-0031).

Crate:  spin
Title:  spin is no longer actively maintained
Date:   2019-11-21
URL:    https://rustsec.org/advisories/RUSTSEC-2019-0031
Dependency tree: 
spin 0.5.2
└── linked_list_allocator 0.6.6
    └── libtock 0.1.0

Full Travis-CI log: https://travis-ci.org/google/OpenSK/builds/646900743.

It seems that spin is an optional dependency and active when the use_spin feature is enabled (which is by default).

The advisory suggests to migrate to https://crates.io/crates/lock_api or https://crates.io/crates/conquer-once (according to the advisory, both should support no_std).

[phil-opp]

Thanks for reporting! From a quick look at the two recommended libraries, it seems like only lock_api is an alternative in our case (conquer-once does not provide a spinlock type). However, the lock_api crate only provides an API and requires users to create a spinlock type themselves. Copy&pasting code and managing it ourselves is not really better than using a dependency that is no longer actively maintained in my opinion.

I opened Amanieu/parking_lot#214 to propose the addition of a Spinlock type to lock_api. Depending on the outcome, it might be a good idea to create a new spinlock crate with this type ourselves.

[phil-opp]

Update: I just created a small spinning_top crate that provides a simple spinlock implementation on top of lock_api: https://docs.rs/spinning_top/0.1.0/spinning_top/. Feedback an reviews are appreciated! If everything looks good, I think we can migrate the linked-list-allocator crate to it.

[gendx]

Thanks @phil-opp! I filed an issue on the RustSec advisory repo to mention this new crate, but maybe you want to wait before advertising it directly on the RUSTSEC-2019-0031 advisory?

In the end, it would all boil down to creating a pull-request to mention spinning_top in https://github.com/RustSec/advisory-db/blob/master/crates/spin/RUSTSEC-2019-0031.toml.

[phil-opp]

I can't guarantee for its correctness of course, but I think it's ready for people to try it. I opened rust-osdev/spinning_top#2 to ask for reviews and I just got an approving review from the author of lock_api, so there don't seem to be any obvious mistakes.

So feel free to add it to the RustSec advisory repo if you like!