[PATCH 5/9] lpfc: Resolve null ptr dereference after an ELS LOGO is aborted

[James Smart <jsmart2021@gmail.com>]

A use-after-free crash can occur after an ELS LOGO is aborted.

Specifically, a nodelist structure is freed and then
ndlp->vport->cfg_log_verbose is dereferenced in lpfc_nlp_get when the
discovery state machine is mistakenly called a second time with
NLP_EVT_DEVICE_RM argument.

Rework lpfc_cmpl_els_logo to prevent the duplicate calls to release a
nodelist structure.

Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
---
 drivers/scsi/lpfc/lpfc_els.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_els.c b/drivers/scsi/lpfc/lpfc_els.c
index 51c505d15410..57e189f62e42 100644
--- a/drivers/scsi/lpfc/lpfc_els.c
+++ b/drivers/scsi/lpfc/lpfc_els.c
@@ -2998,10 +2998,7 @@ lpfc_cmpl_els_logo(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 				 ndlp->nlp_DID, ulp_status,
 				 ulp_word4);
 
-		/* Call NLP_EVT_DEVICE_RM if link is down or LOGO is aborted */
 		if (lpfc_error_lost_link(ulp_status, ulp_word4)) {
-			lpfc_disc_state_machine(vport, ndlp, cmdiocb,
-						NLP_EVT_DEVICE_RM);
 			skip_recovery = 1;
 			goto out;
 		}
@@ -3021,18 +3018,10 @@ lpfc_cmpl_els_logo(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		spin_unlock_irq(&ndlp->lock);
 		lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 					NLP_EVT_DEVICE_RM);
-		lpfc_els_free_iocb(phba, cmdiocb);
-		lpfc_nlp_put(ndlp);
-
-		/* Presume the node was released. */
-		return;
+		goto out_rsrc_free;
 	}
 
 out:
-	/* Driver is done with the IO.  */
-	lpfc_els_free_iocb(phba, cmdiocb);
-	lpfc_nlp_put(ndlp);
-
 	/* At this point, the LOGO processing is complete. NOTE: For a
 	 * pt2pt topology, we are assuming the NPortID will only change
 	 * on link up processing. For a LOGO / PLOGI initiated by the
@@ -3059,6 +3048,10 @@ lpfc_cmpl_els_logo(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 				 ndlp->nlp_DID, ulp_status,
 				 ulp_word4, tmo,
 				 vport->num_disc_nodes);
+
+		lpfc_els_free_iocb(phba, cmdiocb);
+		lpfc_nlp_put(ndlp);
+
 		lpfc_disc_start(vport);
 		return;
 	}
@@ -3075,6 +3068,10 @@ lpfc_cmpl_els_logo(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 					NLP_EVT_DEVICE_RM);
 	}
+out_rsrc_free:
+	/* Driver is done with the I/O. */
+	lpfc_els_free_iocb(phba, cmdiocb);
+	lpfc_nlp_put(ndlp);
 }
 
 /**
-- 
2.26.2