Update Ping.Windows.cs for async task handling

src/libraries/System.Net.Ping/src/System/Net/NetworkInformation/Ping.Windows.cs

@@ -47,7 +47,8 @@ private Task<PingReply> DoSendPingCore(IPAddress address, byte[] buffer, int tim
             TaskCompletionSource<PingReply>? tcs = null;
             if (isAsync)
             {
-                _taskCompletionSource = tcs = new TaskCompletionSource<PingReply>();
+                _taskCompletionSource = tcs = new TaskCompletionSource<PingReply>(TaskCreationOptions.RunContinuationsAsynchronously);
+
             }
 
             _ipv6 = (address.AddressFamily == AddressFamily.InterNetworkV6);
@@ -303,17 +304,18 @@ private void PingCallback()
             }
         }
 
-        // Copies _requestBuffer into unmanaged memory for async icmpsendecho APIs.
+        // Copies _requestBuffer into unmanaged memory for async icmpsendecho APIs
         private unsafe void SetUnmanagedStructures(byte[] buffer)
         {
+            _requestBuffer?.Dispose();
             _requestBuffer = SafeLocalAllocHandle.LocalAlloc(buffer.Length);
-            byte* dst = (byte*)_requestBuffer.DangerousGetHandle();
-            for (int i = 0; i < buffer.Length; ++i)
+            fixed (byte* sourcePtr = buffer)
             {
-                dst[i] = buffer[i];
+                Span<byte> source = new Span<byte>(sourcePtr, buffer.Length);
+                Span<byte> destination = new Span<byte>(_requestBuffer.DangerousGetHandle().ToPointer(), buffer.Length);
+                source.CopyTo(destination);
             }
         }
-
         // Releases the unmanaged memory after ping completion.
         private void FreeUnmanagedStructures()
         {