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mdec: check for out of bounds read

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Bug-Id: CID 1257501
CC: libav-stable@libav.org

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 2c63081b48)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Federico Tomassetti 2015-02-18 12:11:43 +00:00 committed by Michael Niedermayer
parent 51b911e948
commit ea0f616a57
1 changed files with 13 additions and 7 deletions
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20
libavcodec/mdec.c
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@ -88,7 +88,12 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
if (level == 127) {
break;
} else if (level != 0) {
i += run;
i += run;
if (i > 63) {
av_log(a->avctx, AV_LOG_ERROR,
"ac-tex damaged at %d %d\n", a->mb_x, a->mb_y);
return AVERROR_INVALIDDATA;
}
j = scantable[i];
level = (level * qscale * quant_matrix[j]) >> 3;
level = (level ^ SHOW_SBITS(re, &a->gb, 1)) - SHOW_SBITS(re, &a->gb, 1);
@ -98,8 +103,13 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
run = SHOW_UBITS(re, &a->gb, 6)+1; LAST_SKIP_BITS(re, &a->gb, 6);
UPDATE_CACHE(re, &a->gb);
level = SHOW_SBITS(re, &a->gb, 10); SKIP_BITS(re, &a->gb, 10);
i += run;
j = scantable[i];
i += run;
if (i > 63) {
av_log(a->avctx, AV_LOG_ERROR,
"ac-tex damaged at %d %d\n", a->mb_x, a->mb_y);
return AVERROR_INVALIDDATA;
}
j = scantable[i];
if (level < 0) {
level = -level;
level = (level * qscale * quant_matrix[j]) >> 3;
@ -110,10 +120,6 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
level = (level - 1) | 1;
}
}
if (i > 63) {
av_log(a->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", a->mb_x, a->mb_y);
return AVERROR_INVALIDDATA;
}
block[j] = level;
}