🛡️ GHSA-8mj7-wxmc-f424 — neon

Use after free in Neon external buffers

Neon provides functionality for creating JavaScript ArrayBuffer (and the Buffer subtype) instances backed by bytes allocated outside of V8/Node. The [JsArrayBuffer::external](https://docs.rs/neon/0.10.0/neon/types/struct.JsArrayBuffer.html#method.external) and [JsBuffer::external](https://docs.rs/neon/0.10.0/neon/types/struct.JsBuffer.html#method.external) did not require T: 'static prior to Neon 0.10.1. This allowed creating an externally backed buffer from types that may be freed while they are still referenced by a JavaScript ArrayBuffer.

The following example demonstrates use after free. It compiles on versions <0.10.1 and fails to compile afterward.

```rust

pub fn soundness_hole(mut cx: FunctionContext) -> JsResult<JsArrayBuffer> {

let mut data = vec![0u8, 1, 2, 3];

// Creating an external from &mut [u8] instead of Vec<u8> since there is a blanket impl

// of AsMut<T> for &mut T

let buf = JsArrayBuffer::external(&mut cx, data.as_mut_slice());

// buf is still holding a reference to data!

drop(data);

Ok(buf)

}

```