[FFmpeg-cvslog] avfilter/af_join: Fix crash in join filter

[Nikolas Bowe]

ffmpeg | branch: master | Nikolas Bowe <nbowe-at-google.com at ffmpeg.org> | Fri Feb  2 15:11:04 2018 -0800| [c86490c49a3d0683b2f63338430a369c174e2bd5] | committer: Michael Niedermayer

avfilter/af_join: Fix crash in join filter

Previously if ff_outlink_frame_wanted() returned 0 it could dereference a null pointer when trying to read nb_samples.

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c86490c49a3d0683b2f63338430a369c174e2bd5
---

 libavfilter/af_join.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavfilter/af_join.c b/libavfilter/af_join.c
index cf5131e8dc..4f86e13558 100644
--- a/libavfilter/af_join.c
+++ b/libavfilter/af_join.c
@@ -485,6 +485,9 @@ static int activate(AVFilterContext *ctx)
                 return 0;
             }
         }
+        if (!s->input_frames[0]) {
+            return 0;
+        }
     }
 
     nb_samples = s->input_frames[0]->nb_samples;