If a tokio::sync::oneshot channel is closed (via the oneshot::Receiver::close method), a data race may occur if the oneshot::Sender::send method is called while the corresponding oneshot::Receiver is awaited or calling try_recv.

When these methods are called concurrently on a closed channel, the two halves of the channel can concurrently access a shared memory location, resulting in a data race. This has been observed to cause memory corruption.

Note that the race only occurs when both halves of the channel are used after the Receiver half has called close. Code where close is not used, or where the Receiver is not awaited and try_recv is not called after calling close, is not affected.

See tokio#4225 for more details.

Path resolution in warp::filters::fs::dir didn't correctly validate Windows paths meaning paths like /foo/bar/c:/windows/web/screen/img101.png would be allowed and respond with the contents of c:/windows/web/screen/img101.png. Thus users could potentially read files anywhere on the filesystem.

This only impacts Windows. Linux and other unix likes are not impacted by this.

The following presentation at this year's DEF CON was brought to our attention on the Diesel Gitter Channel:

SQL Injection isn't Dead: Smuggling Queries at the Protocol Level
http://web.archive.org/web/20240812130923/https://media.defcon.org/DEF%20CON%2032/DEF%20CON%2032%20presentations/DEF%20CON%2032%20-%20Paul%20Gerste%20-%20SQL%20Injection%20Isn't%20Dead%20Smuggling%20Queries%20at%20the%20Protocol%20Level.pdf
(Archive link for posterity.) Essentially, encoding a value larger than 4GiB can cause the length prefix in the protocol to overflow, causing the server to interpret the rest of the string as binary protocol commands or other data.

It appears Diesel does perform truncating casts in a way that could be problematic, for example: https://github.com/diesel-rs/diesel/blob/ae82c4a5a133db65612b7436356f549bfecda1c7/diesel/src/pg/connection/stmt/mod.rs#L36

This code has existed essentially since the beginning, so it is reasonable to assume that all published versions <= 2.2.2 are affected.

Mitigation

The prefered migration to the outlined problem is to update to a Diesel version newer than 2.2.2, which includes fixes for the problem.

As always, you should make sure your application is validating untrustworthy user input. Reject any input over 4 GiB, or any input that could encode to a string longer than 4 GiB. Dynamically built queries are also potentially problematic if it pushes the message size over this 4 GiB bound.

For web application backends, consider adding some middleware that limits the size of request bodies by default.

Resolution

Diesel now uses #[deny] directives for the following Clippy lints:

• cast_possible_truncation
• cast_possible_wrap
• cast_sign_loss

to prevent casts that will lead to precision loss or other trunctations. Additionally we performed an audit of the relevant code.

A fix is included in the 2.2.3 release.