fuzz: weekly regression seeds (2026-05-03)

[lilith]

Weekly automated fuzz sweep for webpx.

New crashes

Target	Seed	Size	Repro?
decode_static	decode_static-crash-b2b18e4b4545	12 B	already-fixed
limits_boundaries	limits_boundaries-crash-9947b87f07e9	70 B	already-fixed

Both are OOM crashes (exit status: 71). The inputs trick WebPAllocateDecBuffer into attempting an ~8 GB allocation (malloc(8617814172)) via crafted width/height fields. The stable regression harness (fuzz_regression_seeds_do_not_panic) passes for both — the Rust wrapper returns an Err rather than panicking, and the decode_static harness has a MAX_PIXEL_BYTES guard (256 MB) that short-circuits before reaching the allocation site. The OOM only fires under libFuzzer's memory-limit interceptor.

Seeds are kept as cheap regression coverage to ensure the graceful-error path stays in place.

Per-target stats

Target	Execs	Coverage (cov/ft)	New seeds
decode_animation	2,752,393	171/280	0
decode_into	264,398	190/231	0
decode_static	~730,000 (OOM)	183/230	1
decode_streaming	2,618,865	241/592	0
decoder_builder	1,273,046	346/532	0
dim_extremes	3,836,862	268/417	0
encode_roundtrip	654,076	354/434	0
image_info	302,350,270	41/42	0
limits_boundaries	~216,000 (OOM)	387/563	1
mux_metadata	65,216,418	130/187	0
stride_extremes	3,109,840	355/574	0
yuv_planes	32,297,120	237/259	0

All targets ran for 600 s wall time (4 targets in parallel per batch on a 4-core machine, 3 batches total). No timeouts exceeded the 12-minute ceiling.

Notes

• 4 new fuzz targets beyond the expected 8 were discovered (dim_extremes, limits_boundaries, stride_extremes, yuv_planes) — all swept.
• decode_static and limits_boundaries exited early (before the 600 s timer fired) due to the OOM condition; exec counts are approximate from the last corpus pulse line in the log.
• No oversized minimizations (both POCs fit well under the 8 KB ceiling: 12 B and 70 B).
• cargo fuzz tmin produced multiple intermediate files; the smallest was selected in each case.

https://claude.ai/code/session_01L1AKVU8TbCYXhZc6QYGgMh

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Generated by Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.51%. Comparing base (27b8012) to head (830c253).

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #7      +/-   ##
==========================================
+ Coverage   77.24%   77.51%   +0.27%     
==========================================
  Files          18       18              
  Lines        4390     4390              
==========================================
+ Hits         3391     3403      +12     
+ Misses        999      987      -12     

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