From e64046644684707a442838ab0a3f97b893fa712b Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Tue, 2 Jun 2009 01:34:12 +0000
Subject: [PATCH]  - Fix a potential crash in IoGetLowerDeviceObject if nothing
 is attached to us

svn path=/trunk/; revision=41249
---
 reactos/ntoskrnl/io/iomgr/device.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/reactos/ntoskrnl/io/iomgr/device.c b/reactos/ntoskrnl/io/iomgr/device.c
index 051bf648aad..1a5bc54532c 100644
--- a/reactos/ntoskrnl/io/iomgr/device.c
+++ b/reactos/ntoskrnl/io/iomgr/device.c
@@ -1186,8 +1186,12 @@ IoGetLowerDeviceObject(IN PDEVICE_OBJECT DeviceObject)
         /* Get the Lower Device Object */
         LowerDeviceObject = DeviceExtension->AttachedTo;
 
-        /* Reference it */
-        ObReferenceObject(LowerDeviceObject);
+        /* Check that we got a valid device object */
+        if (LowerDeviceObject)
+        {
+            /* We did so let's reference it */
+            ObReferenceObject(LowerDeviceObject);
+        }
     }
 
     /* Return it */