libvpx: Pull from upstream

source/libvpx/vp9/decoder/vp9_decoder.c

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 242 matching lines @@
   if (setjmp(cm->error.jmp)) {
     cm->error.setjmp = 0;
 
     // We do not know if the missing frame(s) was supposed to update
     // any of the reference buffers, but we act conservative and
     // mark only the last buffer as corrupted.
     //
     // TODO(jkoleszar): Error concealment is undefined and non-normative
     // at this point, but if it becomes so, [0] may not always be the correct
     // thing to do here.
-    if (cm->frame_refs[0].idx != INT_MAX)
+    if (cm->frame_refs[0].idx != INT_MAX && cm->frame_refs[0].buf != NULL)
       cm->frame_refs[0].buf->corrupted = 1;
 
-    if (cm->frame_bufs[cm->new_fb_idx].ref_count > 0)
+    if (cm->new_fb_idx > 0 && cm->frame_bufs[cm->new_fb_idx].ref_count > 0)
       cm->frame_bufs[cm->new_fb_idx].ref_count--;
 
     return -1;
   }
 
   cm->error.setjmp = 1;
 
   vp9_decode_frame(pbi, source, source + size, psource);
 
   swap_frame_buffers(pbi);
@@ skipping 36 matching lines @@
 
 #if CONFIG_VP9_POSTPROC
   ret = vp9_post_proc_frame(&pbi->common, sd, flags);
 #else
   *sd = *pbi->common.frame_to_show;
   ret = 0;
 #endif /*!CONFIG_POSTPROC*/
   vp9_clear_system_state();
   return ret;
 }