Colibri loads model directories and safetensors from mirrors it does not
control, so the file's declared shapes and byte spans are attacker-influenced
input. Three memory-safety holes on that boundary, independently confirmed
(incl. a from-scratch adversarial audit that re-derived the same two) and
present in the shipped v1.0.0:
- st.h st_read_f32: numel came from the shape, nbytes from the offsets, with
no cross-check. A crafted tensor whose shape inflates numel past nbytes made
the BF16/F16 loop read past the malloc'd raw buffer and the F32 memcpy write
past the caller's config-sized destination (heap OOB read + write). Now
enforce numel*esz == nbytes before any copy.
- st.h header parse: the shape product could overflow int64 to a small/negative
numel that would then pass the cross-check. Guard each multiply.
- glm.c qt_resolve_fmt (new, replaces the three duplicated "?1:?2:3" fmt sites
in qt_from_disk and both expert_load arms): the old inference SILENTLY fell
to int2 for any unrecognized weight byte count, so a too-short weight became
a valid int2 whose matmul read O*I nibbles past the buffer; and an oversized
scale array overflowed the per-row t->s. Now the weight bytes must match a
known int8/int4/int2 layout and the scale array must match the expected
per-row (O) or grouped (O*ng) cardinality, else refuse.
- glm.c config/generation_config slurp: unbounded ftell -> malloc(n+1) gave a
hostile file a load-time OOM, and on malloc failure b[got]=0 was a NULL
deref. Cap at 256 MB and NULL-check.
Verified: TF token-exactness unchanged on every quant format (full-precision
32/32, int4 11/32, int2 1/32, mix 5/32 -- byte-identical to the pre-change
binary); fmt=4 grouped path preserved (the scale check is by construction the
same condition detect_group_size already imposed); a hand-crafted hostile
safetensors is refused cleanly; ASan+UBSan clean on legit and hostile loads
(only the pre-existing intentional startup leaks remain).
These are the C trust-boundary items of #368, landed as a minimal standalone
fix; the server-side and build items of that PR follow via its rebase.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
JustVugg
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