linux-kernel - Re: [PATCH 3/4][Trivial] lib/kobject.c : Check ktype in kobject_add

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Date:	Mon, 23 Apr 2012 13:40:48 -0700
From:	greg <gregkh@...uxfoundation.org>
To:	yan <clouds.yan@...il.com>
Cc:	kernel <linux-kernel@...r.kernel.org>,
	message <message.get@...il.com>
Subject: Re: [PATCH 3/4][Trivial] lib/kobject.c : Check ktype in
 kobject_add_internal

On Sat, Apr 21, 2012 at 05:58:31PM +0800, yan wrote:
> If someone calls kobject_init with null kobj_type, kobject_init can 
> detect it. But it does not have a return value, it just dumps stack.
> In this case, a kobject_add after that will result in:
>    -->kobject_add_varg
>     -->kobject_add_internal
>      -->create_dir
>       -->sysfs_create_dir
>        -->sysfs_read_ns_type
>         -->kobj_child_ns_ops
> In the end, it will call ->ktype->child_ns_type directly and we have
> an oops.
> 
> Check ktype before really add a kobject.

But how can we add a kobject without a valid ktype?

At the most, I'd prefer to warn about this, much like we warn about not
having a name, and not just returning an error without a hint as to what
went wrong.

greg k-h
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