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ac3dec: validate channel output mode against channel count

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Damaged frames can lead to a mismatch, which can cause a segfault
due to using an incorrect channel mapping.

CC:libav-stable@libav.org
This commit is contained in:
Justin Ruggles 2013-02-20 11:41:20 -05:00
parent 82ca17ac7a
commit d7c450436f
1 changed files with 8 additions and 6 deletions
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14
libavcodec/ac3dec.c
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@ -1336,8 +1336,10 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
if (!err) {
avctx->sample_rate = s->sample_rate;
avctx->bit_rate = s->bit_rate;
}
/* channel config */
/* channel config */
if (!err || (s->channels && s->out_channels != s->channels)) {
s->out_channels = s->channels;
s->output_mode = s->channel_mode;
if (s->lfe_on)
@ -1356,18 +1358,18 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data,
s->fbw_channels == s->out_channels)) {
set_downmix_coeffs(s);
}
} else if (!s->out_channels) {
s->out_channels = avctx->channels;
if (s->out_channels < s->channels)
s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
} else if (!s->channels) {
av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n");
return AVERROR_INVALIDDATA;
}
avctx->channels = s->out_channels;
/* set audio service type based on bitstream mode for AC-3 */
avctx->audio_service_type = s->bitstream_mode;
if (s->bitstream_mode == 0x7 && s->channels > 1)
avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
/* get output buffer */
avctx->channels = s->out_channels;
frame->nb_samples = s->num_blocks * 256;
if ((ret = ff_get_buffer(avctx, frame)) < 0) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");