From 6af35bd55ba54f34f4ef42e89ed80a9ad3aa3802 Mon Sep 17 00:00:00 2001
From: Lekensteyn <lekensteyn@gmail.com>
Date: Tue, 13 Dec 2011 00:07:30 +0100
Subject: [PATCH] bbswitch: Check for result before deref it

---
 bbswitch.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/bbswitch.c b/bbswitch.c
index 32dd339..255049c 100644
--- a/bbswitch.c
+++ b/bbswitch.c
@@ -63,7 +63,9 @@ static int acpi_optimus_dsm(acpi_handle handle, int func, char *args,
     obj = (union acpi_object *)output.pointer;
 
     if (obj->type == ACPI_TYPE_INTEGER)
-        *result = obj->integer.value;
+        if (result)
+            *result = obj->integer.value;
+
         // REVS (revision number) not found, possibly not an Optimus?
         if (obj->integer.value == 0x80000002) {
             printk(KERN_INFO "bbswitch: Optimus function not found\n");