linux-kernel - [PATCH 5.1 370/405] scsi: lpfc: Fix use-after-free mailbox cmd completion

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Date:   Wed, 29 May 2019 20:06:08 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dick Kennedy <dick.kennedy@...adcom.com>,
        James Smart <jsmart2021@...il.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 370/405] scsi: lpfc: Fix use-after-free mailbox cmd completion

[ Upstream commit 9b1640686470fbbd1c6efb35ada6fe1427ea8d0f ]

When unloading the driver, mailbox commands may be sent without holding a
reference on the ndlp. By the time the mailbox command completes, the ndlp
may have reduced its ref counts and been freed.  The problem was reported
by KASAN.

While unregistering due to driver unload, have the completion noop'd by
setting the ndlp context NULL'd. Due to the unload, no further action was
necessary.  Also, while reviewing this path, the generic nulling of the
context after handling should be slightly moved.

Reported by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Dick Kennedy <dick.kennedy@...adcom.com>
Signed-off-by: James Smart <jsmart2021@...il.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/lpfc/lpfc_hbadisc.c | 4 ++++
 drivers/scsi/lpfc/lpfc_sli.c     | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c b/drivers/scsi/lpfc/lpfc_hbadisc.c
index 676f4bf3f33a3..75e9d46d44d42 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -4873,6 +4873,10 @@ lpfc_unreg_rpi(struct lpfc_vport *vport, struct lpfc_nodelist *ndlp)
 					 * accept PLOGIs after unreg_rpi_cmpl
 					 */
 					acc_plogi = 0;
+				} else if (vport->load_flag & FC_UNLOADING) {
+					mbox->ctx_ndlp = NULL;
+					mbox->mbox_cmpl =
+						lpfc_sli_def_mbox_cmpl;
 				} else {
 					mbox->ctx_ndlp = ndlp;
 					mbox->mbox_cmpl =
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 7d2abb70cf093..dc933b6d7800e 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -2502,8 +2502,8 @@ lpfc_sli_def_mbox_cmpl(struct lpfc_hba *phba, LPFC_MBOXQ_t *pmb)
 			} else {
 				ndlp->nlp_flag &= ~NLP_UNREG_INP;
 			}
+			pmb->ctx_ndlp = NULL;
 		}
-		pmb->ctx_ndlp = NULL;
 	}
 
 	/* Check security permission status on INIT_LINK mailbox command */
-- 
2.20.1