[FFmpeg-devel] [PATCH] avcodec/mjpeg_parser: skip markers after EOI, not by size

[Alex Xu (Hello71)]

The check for m->size >= 0xF000 is intended to avoid skipping too much
garbage data between JPEG frames in test_roman (thus missing next SOI),
but it erroneously also skips valid markers between SOI and SOS. Instead
of this, we should simply skip parsing markers other than SOI after EOI.
That way, we will not accidentally skip over SOI due to some garbage
between frames. There is still a small risk of encountering FFD8 in the
garbage data, but the chance of this is fairly low.

Fixes: https://trac.ffmpeg.org/ticket/8967
---
 libavcodec/mjpeg_parser.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/mjpeg_parser.c b/libavcodec/mjpeg_parser.c
index 16a5902c7c..62b923b625 100644
--- a/libavcodec/mjpeg_parser.c
+++ b/libavcodec/mjpeg_parser.c
@@ -80,10 +80,10 @@ static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_siz
                     pc->frame_start_found=0;
                     pc->state=0;
                     return i-3;
+                } else if((state>>16)==0xFFD9 && (state&0xFFFF)!=0xFFD8){
+                    state= 0xFFD900|(state&0xFF);
                 } else if(state<0xFFD00000 || state>0xFFD9FFFF){
                     m->size= (state&0xFFFF)-1;
-                    if (m->size >= 0xF000)
-                        m->size = 0;
                 }
             }
             if(m->size>0){
-- 
2.34.1