A downloaded (supply-chain) model file was fully trusted by the loader. Three
memory-safety holes, all reachable by pointing the engine at a crafted shard —
demonstrated crashing on pre-fix, now rejected fail-closed:
st.h (safetensors):
- header length `hlen` (u64 from the file) was unbounded before malloc(hlen+1):
a crafted value overflows (malloc(0) then hdr[hlen]=0 OOB) or forces a giant
allocation. Now bounded to the file size and a 512 MB cap; malloc NULL-checked.
- json_get() returns NULL for missing/mistyped fields, but dtype/data_offsets/
shape were dereferenced blind (off->kids[0]) — a header omitting data_offsets
SIGSEGV'd (verified). Now type/arity-checked before use.
- data_offsets [a0,b0] were trusted: b0<a0 gave a negative nbytes -> malloc((size_t))
giant and an oversized memcpy into the caller's buffer in st_read_f32 (heap
overflow); off could point outside the file. Now validated 0<=a0<=b0 and
data_start+b0<=filesize.
json.h: j_parse_val recursed with no depth limit -> stack overflow on nested
input like [[[[...]]]]. Added J_MAX_DEPTH=1024 (headers are ~3 deep); wide-but-
flat objects like the GLM header are unaffected (depth is decremented per return).
eval_glm.py: tempfile.mktemp() -> mkstemp() — closes the TOCTOU/symlink race on
a shared tmp dir (CWE-377).
Network path (openai_server.py + serve SUBMIT parser) audited separately and is
already sound: hmac.compare_digest auth, MAX_BODY cap, resolve()+relative_to
traversal guard, list-form subprocess, bounded/validated SUBMIT header. All 62
tests pass; valid GLM/OLMoE shards load unchanged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Scoring raw completions without GLM's training-time prefix runs the model
out-of-distribution: scores drop and A/B sensitivity distorts (#108). Detect
GLM via config.json model_type and prepend automatically, with a stderr
notice. EVAL_PREFIX (including empty) still overrides for research use.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
JustVugg