music-metadata: uncatchable process crash parsing a crafted `.dsf` (residual of GHSA-v6c2-xwv6-8xf7)

Summary

DsfParser.parseChunks skips an unrecognised chunk's payload with an un-awaited call:

this.tokenizer.ignore(Number(chunkHeader.size) - ChunkHeader.len);   // lib/dsf/DsfParser.js:51 — no await

ChunkHeader.len is 12. A crafted .dsf chunk with id != 'fmt ' and size in 0..11 makes the argument negative; strtok3 (≥ 10.3.5) throws RangeError on a negative ignore. Because the call is fire-and-forget, the rejection is **detached from the parseBuffer() promise chain → unhandled rejection → Node's default (≥ 15) crashes the process — after** parseBuffer() already resolved, so a caller's try/catch catches nothing and is still taken down.

Residual of GHSA-v6c2-xwv6-8xf7: the ASF site was fixed in 11.12.3 (size validation) and strtok3 now throws on negative ignore; the DSF site was never validated, and its missing await escalates that throw into an uncatchable crash.

Root cause (lib/dsf/DsfParser.js:34-56)

while (bytesRemaining >= ChunkHeader.len) {               // ChunkHeader.len = 12
  const chunkHeader = await this.tokenizer.readToken(ChunkHeader);   // { id, size }
  switch (chunkHeader.id) {
    case 'fmt ': { ...; return; }
    default: this.tokenizer.ignore(Number(chunkHeader.size) - ChunkHeader.len); break;  // size<12 -> negative, no await
  }
  bytesRemaining -= chunkHeader.size;
}

strtok3 AbstractTokenizer.ignore (L78-79): if (length < 0) throw new RangeError('ignore length must be ≥ 0 bytes');

Steps to reproduce

repro/ — public API only, Node's default unhandled-rejection mode, try/catch around the parse:

npm install && node poc.mjs

Confirmed on 11.14.0:

[app] parseBuffer() RESOLVED — the caller saw no error to catch.
RangeError: ignore length must be ≥ 0 bytes
    at DsfParser.parseChunks (.../lib/dsf/DsfParser.js:51)
   <process exits non-zero — the "process survived" line never prints>

Impact

DoS: a single crafted .dsf (or any file with the DSD magic) crashes the Node process of any app parsing untrusted audio with music-metadata (2.2M weekly downloads). The crash bypasses the caller's error handling, so even apps that correctly try/catch per-file parsing are killed — one malicious upload can take down a shared server/worker.

Remediation

Add await on line 51 (makes the RangeError a catchable parse error), and validate chunkHeader.size >= ChunkHeader.len before the skip (as the ASF fix did; also guards the loop counter). Audit other parsers for un-awaited tokenizer.ignore()/readToken().

Scope / honesty

Requires the DSF path (a DSD -magic file — normal auto-detection). Relies on Node's default unhandled-rejection mode (throw, default since Node 15); the point is that the standard defensive per-parse try/catch does not protect against it. Crash (availability), not disclosure/RCE. Negatives confirmed alongside: ASF infinite loop fixed; negative-ignore infinite-loop class closed at strtok3; unbounded allocation bounded by strtok3's read bound-check.

Credits

Issue also reported by @ryu7eroo