linux-kernel - Re: [-mm3 PATCH] (Retry) Check the return value of kobject

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Date:	Thu, 5 Apr 2007 11:11:42 +0200
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	WANG Cong <xiyou.wangcong@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	viro@...iv.linux.org.uk
Subject: Re: [-mm3 PATCH] (Retry) Check the return value of kobject_add and
 etc.

On Thu, 5 Apr 2007 12:54:11 +0800,
WANG Cong <xiyou.wangcong@...il.com> wrote:

> --- linux-2.6.21-rc5-mm3/fs/partitions/check.c.orig	2007-03-30 21:35:45.000000000 +0800
> +++ linux-2.6.21-rc5-mm3/fs/partitions/check.c	2007-04-02 21:29:02.000000000 +0800
> @@ -385,10 +385,18 @@ void add_partition(struct gendisk *disk,
>  	p->kobj.parent = &disk->kobj;
>  	p->kobj.ktype = &ktype_part;
>  	kobject_init(&p->kobj);
> -	kobject_add(&p->kobj);
> +	if (kobject_add(&p->kobj)) {
> +		kfree(p);
> +		return;
> +	}
>  	if (!disk->part_uevent_suppress)
>  		kobject_uevent(&p->kobj, KOBJ_ADD);
> -	sysfs_create_link(&p->kobj, &block_subsys.kset.kobj, "subsystem");
> +	if (sysfs_create_link(&p->kobj, &block_subsys.kset.kobj, "subsystem")) {
> +		kobject_uevent(&p->kobj, KOBJ_REMOVE);
> +		kobject_del(&p->kobj);
> +		kfree(p);

You should use kobject_put instead of kfree, since someone could have
(theoretically) obtained a reference on the object after the
kobject_add. (Or just use kobject_unregister, if the delete uevent
isn't suppressed anyway.)

> +		return;
> +	}
>  	if (flags & ADDPART_FLAG_WHOLEDISK) {
>  		static struct attribute addpartattr = {
>  			.name = "whole_disk",
> @@ -396,7 +404,13 @@ void add_partition(struct gendisk *disk,
>  			.owner = THIS_MODULE,
>  		};
> 
> -		sysfs_create_file(&p->kobj, &addpartattr);
> +		if (sysfs_create_file(&p->kobj, &addpartattr)) {
> +			sysfs_remove_link(&p->kobj, "subsystem");
> +			kobject_uevent(&p->kobj, KOBJ_REMOVE);
> +			kobject_del(&p->kobj);
> +			kfree(p);

Same here.

> +			return;
> +		}
>  	}
>  	partition_sysfs_add_subdir(p);
>  	disk->part[part-1] = p;
> 
> 
> 

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