scsi: lpfc: Fix null pointer dereference after failing to issue FLOGI and PLOGI

If lpfc_issue_els_flogi() fails and returns non-zero status, the node
reference count is decremented to trigger the release of the nodelist
structure. However, if there is a prior registration or dev-loss-evt work
pending, the node may be released prematurely.  When dev-loss-evt
completes, the released node is referenced causing a use-after-free null
pointer dereference.

Similarly, when processing non-zero ELS PLOGI completion status in
lpfc_cmpl_els_plogi(), the ndlp flags are checked for a transport
registration before triggering node removal.  If dev-loss-evt work is
pending, the node may be released prematurely and a subsequent call to
lpfc_dev_loss_tmo_handler() results in a use after free ndlp dereference.

Add test for pending dev-loss before decrementing the node reference count
for FLOGI, PLOGI, PRLI, and ADISC handling.

Link: https://lore.kernel.org/r/20220412222008.126521-9-jsmart2021@gmail.comCo-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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_els.c

@@ -1534,10 +1534,13 @@ lpfc_initial_flogi(struct lpfc_vport *vport)
 	/* Reset the Fabric flag, topology change may have happened */
 	vport->fc_flag &= ~FC_FABRIC;
 	if (lpfc_issue_els_flogi(vport, ndlp, 0)) {
-		/* This decrement of reference count to node shall kick off
-		 * the release of the node.
+		/* A node reference should be retained while registered with a
+		 * transport or dev-loss-evt work is pending.
+		 * Otherwise, decrement node reference to trigger release.
 		 */
-		lpfc_nlp_put(ndlp);
+		if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
+		    !(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+			lpfc_nlp_put(ndlp);
 		return 0;
 	}
 	return 1;
@@ -1580,10 +1583,13 @@ lpfc_initial_fdisc(struct lpfc_vport *vport)
 	}
 
 	if (lpfc_issue_els_fdisc(vport, ndlp, 0)) {
-		/* decrement node reference count to trigger the release of
-		 * the node.
+		/* A node reference should be retained while registered with a
+		 * transport or dev-loss-evt work is pending.
+		 * Otherwise, decrement node reference to trigger release.
 		 */
-		lpfc_nlp_put(ndlp);
+		if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
+		    !(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+			lpfc_nlp_put(ndlp);
 		return 0;
 	}
 	return 1;
@@ -1985,6 +1991,7 @@ lpfc_cmpl_els_plogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 	int disc;
 	struct serv_parm *sp = NULL;
 	u32 ulp_status, ulp_word4, did, iotag;
+	bool release_node = false;
 
 	/* we pass cmdiocb to state machine which needs rspiocb as well */
 	cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2073,19 +2080,21 @@ lpfc_cmpl_els_plogi(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 			spin_unlock_irq(&ndlp->lock);
 			goto out;
 		}
-		spin_unlock_irq(&ndlp->lock);
 
 		/* No PLOGI collision and the node is not registered with the
 		 * scsi or nvme transport. It is no longer an active node. Just
 		 * start the device remove process.
 		 */
 		if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD))) {
-			spin_lock_irq(&ndlp->lock);
 			ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
-			spin_unlock_irq(&ndlp->lock);
+			if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+				release_node = true;
+		}
+		spin_unlock_irq(&ndlp->lock);
+
+		if (release_node)
 			lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 						NLP_EVT_DEVICE_RM);
-		}
 	} else {
 		/* Good status, call state machine */
 		prsp = list_entry(((struct lpfc_dmabuf *)
@@ -2296,6 +2305,7 @@ lpfc_cmpl_els_prli(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 	u32 loglevel;
 	u32 ulp_status;
 	u32 ulp_word4;
+	bool release_node = false;
 
 	/* we pass cmdiocb to state machine which needs rspiocb as well */
 	cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2372,14 +2382,18 @@ lpfc_cmpl_els_prli(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		 * it is no longer an active node.  Otherwise devloss
 		 * handles the final cleanup.
 		 */
+		spin_lock_irq(&ndlp->lock);
 		if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD)) &&
 		    !ndlp->fc4_prli_sent) {
-			spin_lock_irq(&ndlp->lock);
 			ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
-			spin_unlock_irq(&ndlp->lock);
+			if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+				release_node = true;
+		}
+		spin_unlock_irq(&ndlp->lock);
+
+		if (release_node)
 			lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 						NLP_EVT_DEVICE_RM);
-		}
 	} else {
 		/* Good status, call state machine.  However, if another
 		 * PRLI is outstanding, don't call the state machine
@@ -2751,6 +2765,7 @@ lpfc_cmpl_els_adisc(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 	struct lpfc_nodelist *ndlp;
 	int  disc;
 	u32 ulp_status, ulp_word4, tmo;
+	bool release_node = false;
 
 	/* we pass cmdiocb to state machine which needs rspiocb as well */
 	cmdiocb->context_un.rsp_iocb = rspiocb;
@@ -2817,13 +2832,17 @@ lpfc_cmpl_els_adisc(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
 		 * transport, it is no longer an active node. Otherwise
 		 * devloss handles the final cleanup.
 		 */
+		spin_lock_irq(&ndlp->lock);
 		if (!(ndlp->fc4_xpt_flags & (SCSI_XPT_REGD | NVME_XPT_REGD))) {
-			spin_lock_irq(&ndlp->lock);
 			ndlp->nlp_flag &= ~NLP_NPR_2B_DISC;
-			spin_unlock_irq(&ndlp->lock);
+			if (!(ndlp->nlp_flag & NLP_IN_DEV_LOSS))
+				release_node = true;
+		}
+		spin_unlock_irq(&ndlp->lock);
+
+		if (release_node)
 			lpfc_disc_state_machine(vport, ndlp, cmdiocb,
 						NLP_EVT_DEVICE_RM);
-		}
 	} else
 		/* Good status, call state machine */
 		lpfc_disc_state_machine(vport, ndlp, cmdiocb,