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ac3: validate end in ff_ac3_bit_alloc_calc_mask 

This fixes an invalid read if end is 0:
     band_end   = ff_ac3_bin_to_band_tab[end-1] + 1;

Depending on what is before the array, this can cause stack smashing,
when band_end becomes too large.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit bc4fee7f2a)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Andreas Cadhalpun 2015-04-16 21:25:26 +02:00 committed by Michael Niedermayer
parent 6458ee5af8
commit 6b1c8797f4
1 changed files with 3 additions and 0 deletions
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libavcodec/ac3.c
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@ -131,6 +131,9 @@ int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
int band_start, band_end, begin, end1; int band_start, band_end, begin, end1;
int lowcomp, fastleak, slowleak; int lowcomp, fastleak, slowleak;
if (end <= 0)
return AVERROR_INVALIDDATA;
/* excitation function */ /* excitation function */
band_start = ff_ac3_bin_to_band_tab[start]; band_start = ff_ac3_bin_to_band_tab[start];
band_end = ff_ac3_bin_to_band_tab[end-1] + 1; band_end = ff_ac3_bin_to_band_tab[end-1] + 1;