pthread/mpegvideo: detect and block attempts to init frames after setup.

This fixes race conditions that ultimately lead to memory corruption.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 11 insertions, 0 deletions

diff --git a/libavcodec/pthread.c b/libavcodec/pthread.c
index 7834922f9f..d8f8858c1e 100644
--- a/libavcodec/pthread.c
+++ b/libavcodec/pthread.c
@@ -932,6 +932,17 @@ static int *allocate_progress(PerThreadContext *p)
     return p->progress[i];
 }
 
+int ff_thread_can_start_frame(AVCodecContext *avctx)
+{
+    PerThreadContext *p = avctx->thread_opaque;
+    if ((avctx->active_thread_type&FF_THREAD_FRAME) && p->state != STATE_SETTING_UP &&
+        (avctx->codec->update_thread_context || (!avctx->thread_safe_callbacks &&
+                avctx->get_buffer != avcodec_default_get_buffer))) {
+        return 0;
+    }
+    return 1;
+}
+
 int ff_thread_get_buffer(AVCodecContext *avctx, AVFrame *f)
 {
     PerThreadContext *p = avctx->thread_opaque;