memrar: Address kernel oops during resource cleanup

Some delayed initialization is performed in this driver.  Make sure
resources that are used during driver clean-up (e.g. during driver's
release() function) are fully initialized before first use.  This is
particularly important for the case when the delayed initialization
isn't completed, leaving behind a partially initialized driver.

Such a scenario can occur when RAR is not available on the platform,
and the driver is release()d.
Signed-off-by: NOssama Othman <ossama.othman@intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/memrar/memrar_handler.c

@@ -279,15 +279,6 @@ static int memrar_init_rar_resources(int rarnum, char const *devname)
 	BUG_ON(!memrar_is_valid_rar_type(rarnum));
 	BUG_ON(rar->allocated);
 
-	mutex_init(&rar->lock);
-
-	/*
-	 * Initialize the process table before we reach any
-	 * code that exit on failure since the finalization
-	 * code requires an initialized list.
-	 */
-	INIT_LIST_HEAD(&rar->buffers.list);
-
 	if (rar_get_address(rarnum, &low, &high) != 0)
 		/* No RAR is available. */
 		return -ENODEV;
@@ -941,9 +932,28 @@ static int memrar_registration_callback(unsigned long rar)
 static int __init memrar_init(void)
 {
 	int err;
+	int i;
 
 	printk(banner);
 
+	/*
+	 * Some delayed initialization is performed in this driver.
+	 * Make sure resources that are used during driver clean-up
+	 * (e.g. during driver's release() function) are fully
+	 * initialized before first use.  This is particularly
+	 * important for the case when the delayed initialization
+	 * isn't completed, leaving behind a partially initialized
+	 * driver.
+	 *
+	 * Such a scenario can occur when RAR is not available on the
+	 * platform, and the driver is release()d.
+	 */
+	for (i = 0; i != ARRAY_SIZE(memrars); ++i) {
+		struct memrar_rar_info * const rar = &memrars[i];
+		mutex_init(&rar->lock);
+		INIT_LIST_HEAD(&rar->buffers.list);
+	}
+
 	err = misc_register(&memrar_miscdev);
 	if (err)
 		return err;