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

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

[Xiyu Yang]

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@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.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

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

[Daniel Wagner]

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

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

[James Smart]

On 5/25/2020 8:12 AM, Daniel Wagner wrote:
> 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

Looked at it here and it looks good.

Reviewed-by: James Smart <james.smart@broadcom.com>

-- james

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

[Martin K. Petersen]

On Mon, 25 May 2020 22:16:24 +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.
> 
> When lpfc_els_unsol_buffer() returns, local variable "ndlp" becomes
> invalid, so the refcount should be decreased to keep refcount balanced.
> 
> [...]

Applied to 5.8/scsi-queue, thanks!

[1/1] scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event
      https://git.kernel.org/mkp/scsi/c/7217e6e694da

-- 
Martin K. Petersen	Oracle Linux Engineering