[FFmpeg-cvslog] avformat/sdsdec: Use av_rescale() to avoid intermediate overflow in duration calculation

[Michael Niedermayer]

ffmpeg | branch: release/3.4 | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 18 16:42:21 2022 +0200| [136189522975e252d303cf9fb9e86bb19a5fe709] | committer: Michael Niedermayer

avformat/sdsdec: Use av_rescale() to avoid intermediate overflow in duration calculation

Fixes: signed integer overflow: 72128794995445727 * 240 cannot be represented in type 'long'
Fixes: 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_SDS_fuzzer-6628185583779840

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit aa8eb1bed075931b0ce0a8bc9a8ff5882830044c)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=136189522975e252d303cf9fb9e86bb19a5fe709
---

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

diff --git a/libavformat/sdsdec.c b/libavformat/sdsdec.c
index 081bb4ca2d..bc8b08446a 100644
--- a/libavformat/sdsdec.c
+++ b/libavformat/sdsdec.c
@@ -112,7 +112,7 @@ static int sds_read_header(AVFormatContext *ctx)
     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
     st->codecpar->channels = 1;
     st->codecpar->sample_rate = sample_period ? 1000000000 / sample_period : 16000;
-    st->duration = (avio_size(pb) - 21) / (127) * s->size / 4;
+    st->duration = av_rescale((avio_size(pb) - 21) / 127,  s->size, 4);
 
     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);