[FFmpeg-cvslog] avcodec/vp9: Do not destroy uninitialized mutexes/conditions

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Thu Sep  2 12:08:10 2021 +0200| [bd95f2f599a6605dafa73b95ca7590aa6a5e941d] | committer: Andreas Rheinhardt

avcodec/vp9: Do not destroy uninitialized mutexes/conditions

Also do not destroy and reinitialize mutexes and conditions when
certain input parameters change. Given that the decoder did not
create these variables at all during init, uninitialized mutexes
and conditions are destroyed before the very first initialization.
This is undefined behaviour and certain threading implementations
like pthreadGC2 crash when it is attempted.

Fix this by initializing these objects once during init and freeing
them in close.

Reported-by: Steve Lhomme <robux4 at ycbcr.xyz>
Reviewed-by: Steve Lhomme <robux4 at ycbcr.xyz>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=bd95f2f599a6605dafa73b95ca7590aa6a5e941d
---

 libavcodec/vp9.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
index 874005a5ae..5c20a7ec5d 100644
--- a/libavcodec/vp9.c
+++ b/libavcodec/vp9.c
@@ -43,8 +43,6 @@ static void vp9_free_entries(AVCodecContext *avctx) {
     VP9Context *s = avctx->priv_data;
 
     if (avctx->active_thread_type & FF_THREAD_SLICE)  {
-        pthread_mutex_destroy(&s->progress_mutex);
-        pthread_cond_destroy(&s->progress_cond);
         av_freep(&s->entries);
     }
 }
@@ -66,9 +64,6 @@ static int vp9_alloc_entries(AVCodecContext *avctx, int n) {
 
         for (i  = 0; i < n; i++)
             atomic_init(&s->entries[i], 0);
-
-        pthread_mutex_init(&s->progress_mutex, NULL);
-        pthread_cond_init(&s->progress_cond, NULL);
     }
     return 0;
 }
@@ -1252,6 +1247,12 @@ static av_cold int vp9_decode_free(AVCodecContext *avctx)
 
     free_buffers(s);
     vp9_free_entries(avctx);
+#if HAVE_THREADS
+    if (avctx->active_thread_type & FF_THREAD_SLICE) {
+        pthread_mutex_destroy(&s->progress_mutex);
+        pthread_cond_destroy(&s->progress_cond);
+    }
+#endif
     av_freep(&s->td);
     return 0;
 }
@@ -1797,6 +1798,13 @@ static av_cold int vp9_decode_init(AVCodecContext *avctx)
     s->last_bpp = 0;
     s->s.h.filter.sharpness = -1;
 
+#if HAVE_THREADS
+    if (avctx->active_thread_type & FF_THREAD_SLICE) {
+        pthread_mutex_init(&s->progress_mutex, NULL);
+        pthread_cond_init(&s->progress_cond, NULL);
+    }
+#endif
+
     for (int i = 0; i < 3; i++) {
         s->s.frames[i].tf.f = av_frame_alloc();
         if (!s->s.frames[i].tf.f)