From 82c72f377a91cfa75fed1102f92ff4685c7e74da Mon Sep 17 00:00:00 2001
From: Ray Strode <rstrode@redhat.com>
Date: Wed, 19 Sep 2018 11:47:35 -0400
Subject: [PATCH] dnd: don't try to access destroyed dragActor

The dragComplete handler incorrectly checks
this._actorDestroyed to see if the drag actor
is destroyed.  The drag actor may not be the same
as the main actor.

The end result is an exception in drop handling,
leading to a shell lockup.

This commit changes the code to always set
this._dragActor to undefined when it's destroyed,
and check for that condition instead of
this._actorDestroyed in the dragComplete handler.

Closes https://gitlab.gnome.org/GNOME/gnome-shell/issues/577
---
 js/ui/dnd.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/js/ui/dnd.js b/js/ui/dnd.js
index 634a7d6d7..6c563a3ba 100644
--- a/js/ui/dnd.js
+++ b/js/ui/dnd.js
@@ -506,6 +506,7 @@ var _Draggable = new Lang.Class({
                             return true;
                         } else
                             this._dragActor.destroy();
+                            this._dragActor = undefined;
                     }
 
                     this._dragInProgress = false;
@@ -565,8 +566,10 @@ var _Draggable = new Lang.Class({
             if (!this._buttonDown)
                 this._dragComplete();
             this.emit('drag-end', eventTime, false);
-            if (!this._dragOrigParent)
+            if (!this._dragOrigParent) {
                 this._dragActor.destroy();
+                this._dragActor = undefined;
+            }
 
             return;
         }
@@ -634,6 +637,7 @@ var _Draggable = new Lang.Class({
             dragActor.set_position(this._dragOrigX, this._dragOrigY);
         } else {
             dragActor.destroy();
+            this._dragActor = undefined;
         }
 
         this.emit('drag-end', eventTime, false);
@@ -641,7 +645,7 @@ var _Draggable = new Lang.Class({
     },
 
     _dragComplete() {
-        if (!this._actorDestroyed)
+        if (this._dragActor)
             Shell.util_set_hidden_from_pick(this._dragActor, false);
 
         this._ungrabEvents();