[FFmpeg-cvslog] avcodec/vp9_superframe_split_bsf: Don't read inexistent data

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Mar 22 23:50:54 2022 +0100| [d311d820a77550740d3b868440e476adaf12a872] | committer: Andreas Rheinhardt

avcodec/vp9_superframe_split_bsf: Don't read inexistent data

Fixes: Out of array read
Fixes: 45137/clusterfuzz-testcase-minimized-ffmpeg_BSF_VP9_SUPERFRAME_SPLIT_fuzzer-4984270639202304

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d311d820a77550740d3b868440e476adaf12a872
---

 libavcodec/vp9_superframe_split_bsf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/vp9_superframe_split_bsf.c b/libavcodec/vp9_superframe_split_bsf.c
index 98f5cc83d0..cddd48119c 100644
--- a/libavcodec/vp9_superframe_split_bsf.c
+++ b/libavcodec/vp9_superframe_split_bsf.c
@@ -51,6 +51,9 @@ static int vp9_superframe_split_filter(AVBSFContext *ctx, AVPacket *out)
             return ret;
         in = s->buffer_pkt;
 
+        if (!in->size)
+            goto passthrough;
+
         marker = in->data[in->size - 1];
         if ((marker & 0xe0) == 0xc0) {
             int length_size = 1 + ((marker >> 3) & 0x3);
@@ -121,6 +124,7 @@ static int vp9_superframe_split_filter(AVBSFContext *ctx, AVPacket *out)
             out->pts = AV_NOPTS_VALUE;
 
     } else {
+passthrough:
         av_packet_move_ref(out, s->buffer_pkt);
     }