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cook: expand dither_tab[], and make sure indexes into it don't overflow.

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Fixes overflows in accessing dither_tab[].

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit 442c3a8cb1785d74f8e2d7ab35b1862b7088436b)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
This commit is contained in:
Ronald S. Bultje 2012-03-08 17:09:27 -08:00 committed by Reinhard Tartler
parent 9980e4df3b
commit 88c3cc019c
2 changed files with 7 additions and 3 deletions
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6
libavcodec/cook.c
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@ -507,7 +507,11 @@ static inline void expand_category(COOKContext *q, int *category,
{
int i;
for (i = 0; i < q->num_vectors; i++)
++category[category_index[i]];
{
int idx = category_index[i];
if (++category[idx] >= FF_ARRAY_ELEMS(dither_tab))
--category[idx];
}
}
/**

4
libavcodec/cookdata.h
View File

@ -36,8 +36,8 @@ static const int expbits_tab[8] = {
52,47,43,37,29,22,16,0,
};
static const float dither_tab[8] = {
0.0, 0.0, 0.0, 0.0, 0.0, 0.176777, 0.25, 0.707107,
static const float dither_tab[9] = {
0.0, 0.0, 0.0, 0.0, 0.0, 0.176777, 0.25, 0.707107, 1.0
};
static const float quant_centroid_tab[7][14] = {