Reported

May 22, 2022

Issued

May 23, 2022 (last modified: June 13, 2023)

Package

neon (crates.io)

Type

Vulnerability

Categories

• memory-corruption
• memory-exposure

Keywords

#use-after-free #incorrect-lifetime

Aliases

• GHSA-8mj7-wxmc-f424

References

• https://github.com/neon-bindings/neon/issues/896

Patched

• >=0.10.1

Unaffected

• <0.8.0

Affected Functions

Version

neon::types::JsArrayBuffer::external

• <0.10.1, >=0.8.0

neon::types::JsBuffer::external

• <0.10.1, >=0.8.0

Description

Neon provides functionality for creating JavaScript ArrayBuffer (and the Buffer subtype) instances backed by bytes allocated outside of V8/Node. The JsArrayBuffer::external and JsBuffer::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.

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)
}

Advisory available under CC0-1.0 license.