Improved stability for mp4 parser when dealing with corrupted FTYP boxes #241
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… MP4 parser to throw errors instead of rejecting the files
…mbling the error scenario in code
linkyndy
approved these changes
Sep 15, 2023
CostinTanasoiu
approved these changes
Sep 19, 2023
RubenWolff-wt
deleted the
MP4_parser_stability_for_non-compliant_files
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About the issue
Every MP4 file should start with a
ftypbox. We rely on that to build a check for magic bytes and return early from the parser.The problem arises when a file matches the header of a
ftypbox but don't actually describe the box correctly -- for instance, bringing a wrong box size. In that case, the box can't be parsed and the file should be discarded.What happens instead is that, due to an issue with the safe navigation, the parser would still try to read from the missing box, resulting in the error
NoMethodError: undefined method[]' for nil:NilClass`.