Add missing if statement

Author: safern

src/System.IO.Pipes/src/System/IO/Pipes/NamedPipeClientStream.Windows.cs

@@ -138,7 +138,6 @@ private void ValidateRemotePipeIsCurrentUser()
         {
             SecurityIdentifier currentUserSid = GetCurrentUser();
             PipeSecurity accessControl = this.GetAccessControl();
-
             IdentityReference remoteOwnerSid = accessControl.GetOwner(typeof(SecurityIdentifier));
             if (remoteOwnerSid != currentUserSid)
             {

src/System.IO.Pipes/src/System/IO/Pipes/PipeStream.Windows.cs

@@ -425,11 +425,14 @@ internal static unsafe Interop.Kernel32.SECURITY_ATTRIBUTES GetSecAttrs(HandleIn
                     secAttrs.bInheritHandle = Interop.BOOL.TRUE;
                 }
 
-                byte[] securityDescriptor = pipeSecurity.GetSecurityDescriptorBinaryForm();
-                pinningHandle = GCHandle.Alloc(securityDescriptor, GCHandleType.Pinned);
-                fixed (byte* pSecurityDescriptor = securityDescriptor)
+                if (pipeSecurity != null)
                 {
-                    secAttrs.lpSecurityDescriptor = (IntPtr)pSecurityDescriptor;
+                    byte[] securityDescriptor = pipeSecurity.GetSecurityDescriptorBinaryForm();
+                    pinningHandle = GCHandle.Alloc(securityDescriptor, GCHandleType.Pinned);
+                    fixed (byte* pSecurityDescriptor = securityDescriptor)
+                    {
+                        secAttrs.lpSecurityDescriptor = (IntPtr)pSecurityDescriptor;
+                    }
                 }
             }