Eyevinn / mp4ff / 34779805469

82%

Build Type

push

github

Committed by tobbee

Commit Message

fix(mp4): reject undersized boxes instead of underflowing the size

A box whose declared size is smaller than the fixed fields preceding its
children leaves startPos past endPos. dref, stsd and trep read their
children from 16 bytes in and meta from a computed offset, none of them
checking the size first, so endPos-startPos wrapped and the error
reported a parent size of about 1.8e19. Guard in both
DecodeContainerChildren and DecodeContainerChildrenSR, naming the
declared and the minimum size, which also makes every subtraction after
the guard safe.

DecodeEsdsSR had the same shape in hdr.Size-12. The wrapped value went
to DecodeESDescriptor, which ignores the parameter today, so nothing
misbehaved yet. Both the check and the descriptor size now measure the
payload rather than hdr.Size, which hardcoded an 8-byte header and would
be wrong for a box carrying an extended size.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Coverage Stats

12 of 12 new or added lines in 2 files covered. (100.0%)

4 existing lines in 2 files now uncovered.

22098 of 26925 relevant lines covered (82.07%)

0.82 hits per line