[vorbis-dev] Extra data in header packets

[Martin C. Martin]

Hi,

>From my understanding, if someone were to modify the Vorbis encoder to
include extra data at the end of any of the three header packets, then
the decode will silently ignore it.  That's because the only EOP check
is for the 1 bit added at the end of each packet.  If there were extra
data after that EOP bit, it would be silently ignored.  Right?

If I want to consider extra data like that to be an error, then after
the following line:

  if(oggpack_read(opb,1)!=1)goto err_out; /* top level EOP check */

I could add:

  /* Consume rest of byte */
  oggpack_read(opb, 7);
  /* Is there any more data? */
  if (oggpack_read(opb, 1) != -1) goto err_out;

I'd have to do that in three places, once each in _vorbis_unpack_info,
_vorbis_unpack_comment and _vorbis_unpack_books.

Is that right?  Would that work?

Thanks,
Martin

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