Guard against oversized PICT canvas allocation - #15
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convert_pict_to_image() read the canvas rectangle as four signed 16-bit ints straight from the file and immediately allocated a 4-byte-per-pixel white canvas from width*height, with no bounds check. A malformed PICT declaring a ~65535x65535 canvas forces a multi-gigabyte allocation from only a few input bytes (memory-exhaustion DoS when extracting an untrusted resource fork, since PICT is a standard converter). Reject negative or implausibly large canvas dimensions with PICTError before allocating. The JSON extractor already catches PICTError and falls back to a base16 dump, so a bad PICT degrades gracefully instead of taking down the process.
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Problem
convert_pict_to_image()reads the canvas rectangle as four signed 16-bit ints straight from the file, then immediately allocates a 4-byte-per-pixel white canvas fromwidth * heightwith no bounds check:A malformed PICT declaring a maximal canvas (
top=-32768, left=-32768, bottom=32767, right=32767→ 65535×65535) forces a ~17 GB allocation from only a few input bytes. SincePICTis a standard converter, this fires automatically while extracting an untrusted resource fork — a memory-exhaustion DoS.Fix
Reject negative or implausibly large canvas dimensions with
PICTErrorbefore allocating (cap at ~64 megapixels — far beyond any legitimate classic QuickDraw picture). The JSON extractor already catchesPICTErrorand falls back to a base16 dump, so a bad PICT degrades gracefully instead of taking down the process. The cap is a named constant, easy to tune.Prepared with Claude Fable 5 (Low effort mode). Please review before merging.