[FFmpeg-cvslog] avformat/iamfdec: Check side_substream_id before use

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Apr 23 01:36:43 2025 +0200| [9980a0b9b1ff1872c2ac37e9a709529421446ed5] | committer: Michael Niedermayer

avformat/iamfdec: Check side_substream_id before use

Fixes: poc-iamf-2025-04

Found-by: 苏童 <220235212 at seu.edu.cn>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9980a0b9b1ff1872c2ac37e9a709529421446ed5
---

 libavformat/iamfdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/iamfdec.c b/libavformat/iamfdec.c
index 0f273bdd43..3a6276dcde 100644
--- a/libavformat/iamfdec.c
+++ b/libavformat/iamfdec.c
@@ -126,7 +126,7 @@ static int iamf_read_header(AVFormatContext *s)
 
         // Swap back and side stream ids as our native channel layout ordering doen't match the
         // order from ITU-R - BS.2051-3 for Systems I and J (where side channels come before back ones).
-        if (back_substream_id >= 0 && av_channel_layout_compare(&layer->ch_layout,
+        if (back_substream_id >= 0 && side_substream_id >= 0 && av_channel_layout_compare(&layer->ch_layout,
                                                                 &(AVChannelLayout)AV_CHANNEL_LAYOUT_9POINT1POINT6)) {
             const IAMFSubStream *back_substream = &audio_element->substreams[back_substream_id];
             const IAMFSubStream *side_substream = &audio_element->substreams[side_substream_id];