Miri failure in simple::Message::alloc

[varies-rust]

Problem:

I found a sanitizer/Miri failure reachable through public crate APIs using safe Rust code. I may be missing crate-specific preconditions, but the behavior looks worth checking because safe callers should not be able to trigger undefined behavior.

• Crate: s2n-quic-platform

• Version tested: 0.79.0

• API paths with similar failures observed:

  • message::simple::Message::alloc
  • message::Storage::new

• src/message/simple.rs:122: alloc(entries, payload_len, offset) builds the message storage layout.

• src/message.rs:42: Storage::new calls alloc_zeroed(layout) and expects a non-null allocation pointer.

Readable equivalent PoC:

#[test]
fn poc() {
    let _ = s2n_quic_platform::message::simple::Message::alloc(0, 0, 0);
}

Miri undefined behavior: error: Undefined Behavior: creating allocation with size 0

Need By Date:

This is a potential soundness issue of low priority.

Solution:

Brief reasoning:

• The constructor can reach a zero-size layout and then forces it through NonNull::new(...).expect(...).
• Zero-sized message layouts need an explicit representation, not a raw non-null allocation assumption.

Suggested fix:

• Reject zero-sized combinations or use a dangling non-null sentinel and skip deallocation for that case.

Out of scope: