From 1146a7e3a0f74bf92b5d55e82c827d9862c29fdd Mon Sep 17 00:00:00 2001
From: He Junyan <junyan.he@intel.com>
Date: Fri, 6 Nov 2020 15:36:01 +0800
Subject: [PATCH] glbasefilter: Need to check the display before lock it.

In find_gl_context_unlocked(), the display of filter may be NULL
and can cause crash if we directly access and lock it.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/922>
---
 gst-libs/gst/gl/gstglbasefilter.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gst-libs/gst/gl/gstglbasefilter.c b/gst-libs/gst/gl/gstglbasefilter.c
index 86710733a4..40f37e1f81 100644
--- a/gst-libs/gst/gl/gstglbasefilter.c
+++ b/gst-libs/gst/gl/gstglbasefilter.c
@@ -541,6 +541,11 @@ gst_gl_base_filter_find_gl_context_unlocked (GstGLBaseFilter * filter)
 
   _find_local_gl_context_unlocked (filter);
 
+  if (!filter->display) {
+    GST_WARNING_OBJECT (filter, "filter has NULL display.");
+    return FALSE;
+  }
+
   if (!filter->context) {
     GST_OBJECT_LOCK (filter->display);
     do {