fix(iff): detect corrupt chunk sizes, flags, channel configs#5268
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lgritz wants to merge 2 commits into
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fix(iff): detect corrupt chunk sizes, flags, channel configs#5268lgritz wants to merge 2 commits into
lgritz wants to merge 2 commits into
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Detect and rejecct corrupt chunk sizes, flags, and channel configurations in the header. Assisted-by: Claude Code / Claude Opus 4.8 Signed-off-by: Larry Gritz <lg@larrygritz.com>
A crafted Maya IFF with the TBHD ZBUFFER flag set but RGBA clear took the
ZBUFFER-only branch, which set rgba_count=1/rgba_bits=32 while leaving
zbuffer=0. open() then exposed the image as 1-channel UINT16 (so callers
size their tile buffer from ImageSpec::tile_bytes(true)), but the internal
pixel_bytes() stayed 32-bit. read_native_tile() copied by the internal
pixel size, writing past the smaller caller buffer -- a heap out-of-bounds
write.
Such files can never be decoded anyway: readimg()'s tile loop only handles
8- and 16-bit RGBA pixels and explicitly errors on 32-bit. So reject
ZBUFFER-only headers at open() instead of fabricating an inconsistent spec.
Also:
- Generalize the channel-config check to require rgba_count in {3,4}, which
additionally rejects headers with no color flags at all.
- Clear m_buf when readimg() fails. readimg() resizes m_buf before decoding,
so a partial/failed decode left a non-empty buffer that a later tile
request would reuse, skipping the (failed) decode and copying stale data.
Adds regression test src/zbuffer_only.iff.
Assisted-by: Claude Code / Claude Opus 4.8
Signed-off-by: Larry Gritz <lg@larrygritz.com>
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I have amended this PR to handle an additional related case. |
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Detect and reject corrupt chunk sizes, flags, and channel configurations in the header.
Assisted-by: Claude Code / Claude Opus 4.8