[PATCH] drivers-core: nullify private pointer on device-release

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

Device structures can be reused over multiple device_add / device_release 
cycles. As the private pointer in that struct is checked for NULL, it has 
to be nullified after freeing the private data. Failure to do so causes a 
use after free bug.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 6bee6af..3c9f449 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -122,6 +122,7 @@ static void device_release(struct kobject *kobj)
 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
 			"function, it is broken and must be fixed.\n",
 			dev_name(dev));
+	dev->p = NULL;
 	kfree(p);
 }