linux-kernel - [PATCH] scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event

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Date:   Mon, 25 May 2020 22:16:24 +0800
From:   Xiyu Yang <xiyuyang19@...an.edu.cn>
To:     James Smart <james.smart@...adcom.com>,
        Dick Kennedy <dick.kennedy@...adcom.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, kjlu@....edu,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event

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.

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.

Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 drivers/scsi/lpfc/lpfc_els.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index 80d1e661b0d4..35fbcb4d52eb 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -8514,6 +8514,8 @@ lpfc_els_unsol_buffer(struct lpfc_hba *phba, struct lpfc_sli_ring *pring,
 	spin_lock_irq(shost->host_lock);
 	if (ndlp->nlp_flag & NLP_IN_DEV_LOSS) {
 		spin_unlock_irq(shost->host_lock);
+		if (newnode)
+			lpfc_nlp_put(ndlp);
 		goto dropit;
 	}
 	spin_unlock_irq(shost->host_lock);
-- 
2.7.4