[FFmpeg-cvslog] takdec: ensure chan2 is a valid channel index

[Andreas Cadhalpun]

ffmpeg | branch: release/2.7 | Andreas Cadhalpun <andreas.cadhalpun at googlemail.com> | Wed Jun 10 00:12:38 2015 +0200| [1051c152f97c0e22436fee3657dc7c31a229aba4] | committer: Michael Niedermayer

takdec: ensure chan2 is a valid channel index

If chan2 is not smaller than the number of channels, it can cause
segmentation faults due to dereferencing a NULL pointer.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit 05c57ba2f42324da2fdc93d83d65bb68dd637613)

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1051c152f97c0e22436fee3657dc7c31a229aba4
---

 libavcodec/takdec.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libavcodec/takdec.c b/libavcodec/takdec.c
index a453da8..4225030 100644
--- a/libavcodec/takdec.c
+++ b/libavcodec/takdec.c
@@ -801,6 +801,12 @@ static int tak_decode_frame(AVCodecContext *avctx, void *data,
                     if (s->mcdparams[i].present) {
                         s->mcdparams[i].index = get_bits(gb, 2);
                         s->mcdparams[i].chan2 = get_bits(gb, 4);
+                        if (s->mcdparams[i].chan2 >= avctx->channels) {
+                            av_log(avctx, AV_LOG_ERROR,
+                                   "invalid channel 2 (%d) for %d channel(s)\n",
+                                   s->mcdparams[i].chan2, avctx->channels);
+                            return AVERROR_INVALIDDATA;
+                        }
                         if (s->mcdparams[i].index == 1) {
                             if ((nbit == s->mcdparams[i].chan2) ||
                                 (ch_mask & 1 << s->mcdparams[i].chan2))