From 1920b1b6eaebb035805c7dc8ca5f539b6a19b90e Mon Sep 17 00:00:00 2001
From: Bar Arnon <i3arnon@gmail.com>
Date: Thu, 2 Dec 2021 20:25:12 +0200
Subject: [PATCH] Fix race condition between DisconnectAsync and Dispose
 (#16536)

---
 .../engine/remoting/client/RemotingProtocol2.cs  | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/System.Management.Automation/engine/remoting/client/RemotingProtocol2.cs b/src/System.Management.Automation/engine/remoting/client/RemotingProtocol2.cs
index 8b8908b6e6..07446d45fc 100644
--- a/src/System.Management.Automation/engine/remoting/client/RemotingProtocol2.cs
+++ b/src/System.Management.Automation/engine/remoting/client/RemotingProtocol2.cs
@@ -813,7 +813,7 @@ namespace System.Management.Automation.Internal
                     // what thread this callback is made from.  If it was made from a transport
                     // callback event then a deadlock may occur when DisconnectAsync is called on
                     // that same thread.
-                    ThreadPool.QueueUserWorkItem(new WaitCallback(StartDisconnectAsync), RemoteSession);
+                    ThreadPool.QueueUserWorkItem(new WaitCallback(StartDisconnectAsync));
                 }
             }
         }
@@ -821,10 +821,18 @@ namespace System.Management.Automation.Internal
         /// <summary>
         /// WaitCallback method to start an asynchronous disconnect.
         /// </summary>
-        /// <param name="remoteSession"></param>
-        private void StartDisconnectAsync(object remoteSession)
+        /// <param name="state"></param>
+        private void StartDisconnectAsync(object state)
         {
-            ((ClientRemoteSession)remoteSession).DisconnectAsync();
+            var remoteSession = RemoteSession;
+            try
+            {
+                remoteSession?.DisconnectAsync();
+            }
+            catch 
+            {
+                // remoteSession may have already been disposed resulting in unexpected exceptions.
+            }
         }
 
         /// <summary>