The `sync-read-txn` feature of heed all the v0.10 is unsound

[Kerollmops]

A contributor recently discovered that heed's sync-read-txn feature is unsound and should not exist. This feature was implementing Sync on the RoTxn struct, but in fact, it should have only implemented Send. I explained the different implications in an issue comment.

I replaced this feature with the correct read-txn-no-tls, which makes the RoTxn: Send. According to the LMDB documentation and Howard Chu's comments, it is correct to do that. Unfortunately, this change is not yet available as I am working on a big refactor. However, it will be available in v0.20.0.

What should I do? Should I yank all the heed versions even if only a specific feature is affected?

[Shnatsel]

The ideal solution is to backport this change and publish a new release in the v0.10.x series with the fix.

If that is not feasible (the fix depends on other changes made during the refactor), you could file a security advisory telling people not to use the feature. Sadly none of the audit tooling is feature-aware, so the warning will be shown regardless of whether the feature is actually enabled.

I believe yanking is overkill in this case, since it would break workflows even for people who are not affected by the issue.

[Kerollmops]

Thank you very much for your answer 👌

The ideal solution is to backport this change and publish a new release in the v0.10.x series with the fix.

Replacing this feature with another with a new v0.11.1 version is feasible, or even patching the v0.10 series. However, isn't removing a cargo feature in a patch version breaking? It risks breaking the builds. What do you think?

[Shnatsel]

I would prefer releasing a fixed 0.11.x and removing the broken 0.10.x feature at the same time. That way for users who are not affected everything works fine, and the affected users can upgrade to a fixed version.