[FFmpeg-cvslog] avformat/iff: Check nb_channels == 0 in CHNL

[Michael Niedermayer]

ffmpeg | branch: release/7.0 | Michael Niedermayer <michael at niedermayer.cc> | Sat Jun 21 02:01:22 2025 +0200| [1303a167123a096b4b75487a6b9f2a3f0e161684] | committer: Michael Niedermayer

avformat/iff: Check nb_channels == 0 in CHNL

Fixes: division by 0
Fixes: 418396712/clusterfuzz-testcase-minimized-ffmpeg_dem_IFF_fuzzer-6104388018176000
Fixes: 418478219/clusterfuzz-testcase-minimized-ffmpeg_dem_IFF_fuzzer-4569544410857472

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Peter Ross <pross at xvid.org>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 5b1301004bdade13e3fee22081459e339ddd2637)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1303a167123a096b4b75487a6b9f2a3f0e161684
---

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

diff --git a/libavformat/iff.c b/libavformat/iff.c
index 1d6f72443d..1340e78b0a 100644
--- a/libavformat/iff.c
+++ b/libavformat/iff.c
@@ -279,7 +279,7 @@ static int parse_dsd_prop(AVFormatContext *s, AVStream *st, uint64_t eof)
                 return AVERROR_INVALIDDATA;
             st->codecpar->ch_layout.order       = AV_CHANNEL_ORDER_UNSPEC;
             st->codecpar->ch_layout.nb_channels = avio_rb16(pb);
-            if (size < 2 + st->codecpar->ch_layout.nb_channels * 4)
+            if (size < 2 + st->codecpar->ch_layout.nb_channels * 4 || !st->codecpar->ch_layout.nb_channels)
                 return AVERROR_INVALIDDATA;
             if (st->codecpar->ch_layout.nb_channels > FF_ARRAY_ELEMS(dsd_layout)) {
                 avpriv_request_sample(s, "channel layout");