linux-kernel - Re: [PATCH 20/25] sysfs: Rename Support multiple superblocks

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Date:	Thu, 09 Aug 2007 01:42:03 +0900
From:	Tejun Heo <htejun@...il.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Greg KH <greg@...ah.com>, linux-kernel@...r.kernel.org,
	satyam@...radead.org, cornelia.huck@...ibm.com,
	stern@...land.harvard.edu,
	Linux Containers <containers@...ts.osdl.org>, gregkh@...e.de
Subject: Re: [PATCH 20/25] sysfs: Rename Support multiple superblocks

Eric W. Biederman wrote:
>> 	/* Find the first parent which has valid dentry.
>> 	 */
>> 	dentry = NULL;
>> 	cur = sd;
>> 	while (!(dentry = __sysfs_get_dentry(sb, cur))) {
>> 		if (cur->s_flags & SYSFS_FLAG_REMOVED) {
>> 			dentry = ERR_PTR(-ENOENT);
>> 			break;
>> 		}
>> 		cur = cur->s_parent;
>> 	}
> 
> Here we depend on the fact that sysfs_root is pointed to
> by sb->s_root so we know it will always have a dentry.

Hmmm... dentry could be ERR_PTR(-ENOENT) here if the REMOVED flag test
succeeded, right?

>> 	/* from the found dentry, look up depth times */
>> 	while (dentry->d_fsdata != sd) {

And then dereferenced.  The REMOVED test should never succeed there, so
we're probably in the clear but still the code looks a bit scary.

-- 
tejun
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