[PATCH] driver-model: sysfs_release() dangling pointer reference fix

 df_03_sysfs_release_fix.patch

Some attributes are allocated dynamically (e.g. module and device
parameters) and are usually deallocated when the assoicated kobject is
released.  So, it's not safe to access attr after putting the kobject.
Signed-off-by: Tejun Heo <tj@home-tj.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

fs/sysfs/file.c

@@ -330,11 +330,13 @@ static int sysfs_release(struct inode * inode, struct file * filp)
 {
 	struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
 	struct attribute * attr = to_attr(filp->f_dentry);
+	struct module * owner = attr->owner;
 	struct sysfs_buffer * buffer = filp->private_data;
 
 	if (kobj) 
 		kobject_put(kobj);
-	module_put(attr->owner);
+	/* After this point, attr should not be accessed. */
+	module_put(owner);
 
 	if (buffer) {
 		if (buffer->page)