mirror of https://git.ffmpeg.org/ffmpeg.git
avcodec/ac3dec: Check expacc
this is somewhat a magic number, which can be understood from reading section "7.1.2 Exponent Strategy" of the ac3 specification, in short: Three exponents each represented as number 0-4 are grouped together and base-5 encoded, so the maximal correct value is 25*4 + 5*4 + 4 = 124. Reviewed-by: Andreas Cadhalpun <andreas.cadhalpun@googlemail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
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@ -426,6 +426,10 @@ static int decode_exponents(AC3DecodeContext *s,
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group_size = exp_strategy + (exp_strategy == EXP_D45);
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for (grp = 0, i = 0; grp < ngrps; grp++) {
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expacc = get_bits(gbc, 7);
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if (expacc >= 125) {
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av_log(s->avctx, AV_LOG_ERROR, "expacc %d is out-of-range\n", expacc);
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return AVERROR_INVALIDDATA;
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}
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
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