[FFmpeg-cvslog] avformat/demux: Make read_frame_internal() return AVERREOR(EAGAIN) on stuck empty input parser

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Tue Feb  8 20:00:53 2022 +0100| [02699490c14e86105104940c009953081f69432c] | committer: Michael Niedermayer

avformat/demux: Make read_frame_internal() return AVERREOR(EAGAIN) on stuck empty input parser

Fixes: read_frame_internal() which does not return even though both demuxer and parser do return
Fixes: 43717/clusterfuzz-testcase-minimized-ffmpeg_IO_DEMUXER_fuzzer-5206008287330304

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=02699490c14e86105104940c009953081f69432c
---

 libavformat/demux.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libavformat/demux.c b/libavformat/demux.c
index 1620716716..57720f4311 100644
--- a/libavformat/demux.c
+++ b/libavformat/demux.c
@@ -1235,11 +1235,15 @@ static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
     FFFormatContext *const si = ffformatcontext(s);
     int ret, got_packet = 0;
     AVDictionary *metadata = NULL;
+    int empty = 0;
 
     while (!got_packet && !si->parse_queue.head) {
         AVStream *st;
         FFStream *sti;
 
+        if (empty > 1)
+            return AVERROR(EAGAIN);
+
         /* read next packet */
         ret = ff_read_packet(s, pkt);
         if (ret < 0) {
@@ -1330,6 +1334,8 @@ static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
             }
             got_packet = 1;
         } else if (st->discard < AVDISCARD_ALL) {
+            if (pkt->size == 0)
+                empty ++;
             if ((ret = parse_packet(s, pkt, pkt->stream_index, 0)) < 0)
                 return ret;
             st->codecpar->sample_rate = sti->avctx->sample_rate;