# libvorbis (Ogg Vorbis) — 5-MOAD Scan Result: CLEAN

**Target:** xiph/vorbis
**Source:** https://github.com/xiph/vorbis
**Scan Date:** 2026-03-31
**Language:** C

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## MOAD-0001 — CWE-407: Algorithmic Complexity (list membership in loop)

### Candidates investigated

**`lib/floor1.c` — `floor1_look()` neighbor search (lines 233–252)**

Double loop: outer over `n-2` posts (n ≤ VIF_POSIT+2 = 65), inner over `i+2`
prior posts. O(n²) = O(63²) = ~3969 ops. Runs once per codec setup call, not
per frame. Bounded absolutely by spec constant VIF_POSIT=63. Not actionable.

**`lib/res0.c` — `_01class()` / `_2class()` partition threshold scan (lines 441–444, 505–508)**

For each partition value, a linear scan through `possible_partitions` to find
our threshold bracket. Outer loop is over `partvals` (n/grouping, where n is
residue length and grouping is typically 32). Inner scan is at most
`possible_partitions-1` ≤ 63 (6-bit field per spec). Both dimensions are
codec-spec bounded. In practice: 64 partvals × 63 partitions = 4032 comparisons
per frame. Not an O(N²) growth pattern over user-controlled input. Not actionable.

**`lib/psy.c` — `noise_normalize()` qsort call**

Sorts up to `n` floats per partition band. Uses qsort (O(n log n)). CLEAN.

**`lib/floor1.c` — per-frame `floor1_forward_block()` neighbor update (lines 680–689)**

Two inner loops over `posts` positions when a new split post is accepted. Both
break immediately on first mismatch — amortized O(posts) total across all splits
per frame. Not O(posts²). CLEAN.

**`lib/vorbisfile.c` — serialno scan (lines 840–841, 1373–1374)**

Linear scan of `vf->serialnos[link]` inside page-reading loop. `vf->links` is
the number of chained bitstreams in the file — typically 1–3 for real files.
Seek-path only, not hot decode path. CLEAN.

### Verdict: CLEAN — no CWE-407 defects

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## MOAD-0002 — Intertangle: shared mutable global state / god object

No mutable process-global state in the encode/decode path. All per-session state
lives in `vorbis_dsp_state`, `vorbis_block`, `vorbis_info` — caller-owned structs.
`lib/misc.c` global tracking (`pointers`, `global_bytes`) is `#ifdef DEBUG_MALLOC`
only — not compiled in production. `mapping0.c` `seq`/`total` statics are inside
`#if 0` dead code block. CLEAN.

---

## MOAD-0003 — Leaked Context: ThreadLocal / thread-scoped request identity

No `pthread_getspecific`, `__thread`, `thread_local`, or equivalent in any
encode/decode path. Pure C library with caller-owned state. CLEAN.

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## MOAD-0004 — CWE-312: credentials or keys logged verbatim

Pure audio codec library. No auth flows, HTTP headers, API keys, or credential
handling anywhere in our codebase. CLEAN.

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## MOAD-0005 — Thundering Herd: unsynchronized cache get+null+compute+put

No caching with unsynchronized double-checked access. `lib/floor0.c`/`floor1.c`
memo arrays are stack-local per-block, passed explicitly. `lib/smallft.c`
trigcache is computed once during `drft_init` in single-threaded setup, never
updated after initialization. CLEAN.