[FFmpeg-cvslog] avformat/bfi: Check chunk_header

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jan 14 18:41:41 2021 +0100| [638a151a877c27a46c15643db26c9ba726feecde] | committer: Michael Niedermayer

avformat/bfi: Check chunk_header

Fixes: signed integer overflow: -2147483648 - 3 cannot be represented in type 'int'
Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_BFI_fuzzer-6665764123836416

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=638a151a877c27a46c15643db26c9ba726feecde
---

 libavformat/bfi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/bfi.c b/libavformat/bfi.c
index 29e2cf8cf4..2dab986f3a 100644
--- a/libavformat/bfi.c
+++ b/libavformat/bfi.c
@@ -69,6 +69,9 @@ static int bfi_read_header(AVFormatContext * s)
     /* Set the total number of frames. */
     avio_skip(pb, 8);
     chunk_header           = avio_rl32(pb);
+    if (chunk_header < 3)
+        return AVERROR_INVALIDDATA;
+
     bfi->nframes           = avio_rl32(pb);
     avio_rl32(pb);
     avio_rl32(pb);