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aac: Keep decode_band_types() from eating all padding at the end of a buffer.

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Due to a shortcoming in the AAC specification, if an all zero buffer is
fed to section data decoding it will never terminate. That means without
a buffer exhaustion check decode_band_types() will consume all input
buffer padding. Worse if a get_bits() implementation that returns zeros
when padding is exhausted is used, the function will never terminate.

The fixes that by added a buffer exhaustion check in the sectioning
decoding loop.

Originally committed as revision 22044 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Alex Converse 2010-02-24 23:56:52 +00:00
parent 3314799368
commit c4a90caae2
1 changed files with 4 additions and 0 deletions
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4
libavcodec/aac.c
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@ -715,6 +715,10 @@ static int decode_band_types(AACContext *ac, enum BandType band_type[120],
while ((sect_len_incr = get_bits(gb, bits)) == (1 << bits) - 1)
sect_end += sect_len_incr;
sect_end += sect_len_incr;
if (get_bits_left(gb) < 0) {
av_log(ac->avccontext, AV_LOG_ERROR, overread_err);
return -1;
}
if (sect_end > ics->max_sfb) {
av_log(ac->avccontext, AV_LOG_ERROR,
"Number of bands (%d) exceeds limit (%d).\n",