linux-kernel - Re: [PATCH] fs: sysfs: Fix reference leak in sysfs_break_active

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Message-ID: <ZfIeQKluEeh7TulW@slm.duckdns.org>
Date: Wed, 13 Mar 2024 11:44:32 -1000
From: Tejun Heo <tj@...nel.org>
To: Alan Stern <stern@...land.harvard.edu>
Cc: Bart Van Assche <bvanassche@....org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs: sysfs: Fix reference leak in
 sysfs_break_active_protection()

On Wed, Mar 13, 2024 at 05:43:41PM -0400, Alan Stern wrote:
> The sysfs_break_active_protection() routine has an obvious reference
> leak in its error path.  If the call to kernfs_find_and_get() fails then
> kn will be NULL, so the companion sysfs_unbreak_active_protection()
> routine won't get called (and would only cause an access violation by
> trying to dereference kn->parent if it was called).  As a result, the
> reference to kobj acquired at the start of the function will never be
> released.
> 
> Fix the leak by adding an explicit kobject_put() call when kn is NULL.
> 
> Signed-off-by: Alan Stern <stern@...land.harvard.edu>
> Fixes: 2afc9166f79b ("scsi: sysfs: Introduce sysfs_{un,}break_active_protection()")
> Cc: Bart Van Assche <bvanassche@....org>
> Cc: <stable@...r.kernel.org>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun