[FFmpeg-cvslog] avformat/asfdec_f: Check for negative ext_len

Michael Niedermayer git at videolan.org
Fri Oct 23 11:34:42 EEST 2020


ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Oct 16 11:13:19 2020 +0200| [209b9ff5c3f337da4a3d82e59b8815eca2737ffa] | committer: Michael Niedermayer

avformat/asfdec_f: Check for negative ext_len

Fixes: Infinite loop
Fixes: 26376/clusterfuzz-testcase-minimized-ffmpeg_dem_PCM_U32LE_fuzzer-6050518830678016
Fixes: 26377/clusterfuzz-testcase-minimized-ffmpeg_dem_TY_fuzzer-4838195726123008
Fixes: 26384/clusterfuzz-testcase-minimized-ffmpeg_dem_G729_fuzzer-5173450337157120
Fixes: 26396/clusterfuzz-testcase-minimized-ffmpeg_dem_PCM_S24BE_fuzzer-5071092206796800

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=209b9ff5c3f337da4a3d82e59b8815eca2737ffa
---

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

diff --git a/libavformat/asfdec_f.c b/libavformat/asfdec_f.c
index ff9107d73f..5b4119a315 100644
--- a/libavformat/asfdec_f.c
+++ b/libavformat/asfdec_f.c
@@ -607,6 +607,8 @@ static int asf_read_ext_stream_properties(AVFormatContext *s, int64_t size)
         ff_get_guid(pb, &g);
         size = avio_rl16(pb);
         ext_len = avio_rl32(pb);
+        if (ext_len < 0)
+            return AVERROR_INVALIDDATA;
         avio_skip(pb, ext_len);
         if (stream_num < 128 && i < FF_ARRAY_ELEMS(asf->streams[stream_num].payload)) {
             ASFPayload *p = &asf->streams[stream_num].payload[i];



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