Re: [PATCH 1/1] Kobject: bail early if no new_parent in kobject_move()

Cornelia Huck
2009-10-05T16:38:58Z

On Thu, 1 Oct 2009 17:50:48 +0300,
Phil Carmody <ext-phil.2.carmody@nokia.com> wrote:

> From: Phil Carmody <ext-phil.2.carmody@nokia.com>
>
> In the absense of kobj->kset, new_parent would remain NULL.
> NULL-dereference shenanighans then ensues in the subsequent
> sysfs_move_dir(..., new_parent) call. Bail early instead.

But sysfs_move_dir(..., NULL) should work and fall back to the sysfs
root...

<looks at code>

It seems that has been broken for some time. Should probably be
something like this instead (uncompiled); I can send it with proper
description and s-o-b once I gave it a test.

---
fs/sysfs/dir.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- linux-2.6.orig/fs/sysfs/dir.c
+++ linux-2.6/fs/sysfs/dir.c
@@ -894,7 +894,8 @@ int sysfs_move_dir(struct kobject *kobj,

mutex_lock(&sysfs_rename_mutex);
BUG_ON(!sd->s_parent);
- new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
+ new_parent_sd = (new_parent_kobj && new_parent_kobj->sd) ?
+ new_parent_kobj->sd : &sysfs_root;

error = 0;
if (sd->s_parent == new_parent_sd)