[FFmpeg-cvslog] avformat/matroskadec: check that channels fit in signed 32bit int

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun May 11 23:18:19 2025 +0200| [05f8c8c4c2b8f3a0b206ecb7e1b5bba68a9820b8] | committer: Michael Niedermayer

avformat/matroskadec: check that channels fit in signed 32bit int

Fixes: signed integer overflow: -1384566925600903168 * 16 cannot be represented in type 'long'
Fixes: 407069502/clusterfuzz-testcase-minimized-ffmpeg_dem_WEBM_DASH_MANIFEST_fuzzer-5159255372267520

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=05f8c8c4c2b8f3a0b206ecb7e1b5bba68a9820b8
---

 libavformat/matroskadec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index d4b7ae112c..29e35e6dd4 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2842,6 +2842,8 @@ static int mka_parse_audio(MatroskaTrack *track, AVStream *st,
     par->sample_rate = track->audio.out_samplerate;
     // channel layout may be already set by codec private checks above
     if (!av_channel_layout_check(&par->ch_layout)) {
+        if (track->audio.channels > INT32_MAX)
+            return AVERROR_PATCHWELCOME;
         par->ch_layout.order = AV_CHANNEL_ORDER_UNSPEC;
         par->ch_layout.nb_channels = track->audio.channels;
     }