Re: [PATCH] scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event

From: Daniel Wagner <dwagner@suse.de>
To: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: James Smart <james.smart@broadcom.com>,
	Dick Kennedy <dick.kennedy@broadcom.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	yuanxzhang@fudan.edu.cn, kjlu@umn.edu,
	Xin Tan <tanxin.ctf@gmail.com>
Subject: Re: [PATCH] scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event
Date: Mon, 25 May 2020 17:12:20 +0200	[thread overview]
Message-ID: <20200525151220.rtwmlobnkmhwhxn5@beryllium.lan> (raw)
In-Reply-To: <1590416184-52592-1-git-send-email-xiyuyang19@fudan.edu.cn>

Hi,

On Mon, May 25, 2020 at 10:16:24PM +0800, Xiyu Yang wrote:
> In order to create or activate a new node, lpfc_els_unsol_buffer()
> invokes lpfc_nlp_init() or lpfc_enable_node() or lpfc_nlp_get(), all of
> them will return a reference of the specified lpfc_nodelist object to
> "ndlp" with increased refcnt.

lpfc_enable_node() is not changing the refcnt.

> When lpfc_els_unsol_buffer() returns, local variable "ndlp" becomes
> invalid, so the refcount should be decreased to keep refcount balanced.
> 
> The reference counting issue happens in one exception handling path of
> lpfc_els_unsol_buffer(). When "ndlp" in DEV_LOSS, the function forgets
> to decrease the refcnt increased by lpfc_nlp_init() or
> lpfc_enable_node() or lpfc_nlp_get(), causing a refcnt leak.
> 
> Fix this issue by calling lpfc_nlp_put() when "ndlp" in DEV_LOSS.

This sounds reasonable. At least the lpfc_nlp_init() and lpfc_nlp_get() case
needs this. And I suppose this is also ok for the lfpc_enable_node().

Reviewed-by: Daniel Wagner <dwagner@suse.de>

Thanks,
Daniel