From cbb4319fb9f02da2a71c69cf9f54e03ba81c8846 Mon Sep 17 00:00:00 2001
From: thorpej <thorpej@NetBSD.org>
Date: Tue, 25 Feb 1997 23:28:09 +0000
Subject: [PATCH] vm_object_shadow(): Add a DIAGNOSTIC check for shadowing a
 null object. From Charles Hannum <mycroft@netbsd.org>

---
 sys/vm/vm_object.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 48e8627b8d8d..0a474ac55c90 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: vm_object.c,v 1.44 1997/02/24 22:19:26 thorpej Exp $	*/
+/*	$NetBSD: vm_object.c,v 1.45 1997/02/25 23:28:09 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1997 Charles M. Hannum.  All rights reserved.
@@ -896,6 +896,11 @@ vm_object_shadow(object, offset, length)
 
 	source = *object;
 
+#ifdef DIAGNOSTIC
+	if (source == NULL)
+		panic("vm_object_shadow: attempt to shadow null object");
+#endif
+
 	/*
 	 * Allocate a new object with the given length
 	 */