[PATCH v2] scsi: lpfc: Add rport validation in lpfc_dev_loss_tmo_callbk

[Vaibhav Nagare <nagarevaibhav@gmail.com>]

  Fix a kernel NULL pointer dereference in lpfc_dev_loss_tmo_callbk()
  when ndlp->vport is NULL during FC remote port deletion.

  The crash occurs during fc_rport_final_delete() when the vport has
  already been cleared on the ndlp structure, but the dev_loss_tmo
  callback is still invoked.

  The driver already has lpfc_rport_invalid() which validates rport,
  rdata, ndlp, and vport. The function lpfc_terminate_rport_io() uses
  this validation, but lpfc_dev_loss_tmo_callbk() does not, leading
  to a NULL pointer dereference when accessing vport->phba.

  Crash signature observed on RHEL 8.10 (4.18.0-553.125.1.el8_10.x86_64):
    BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
    RIP: lpfc_dev_loss_tmo_callbk+0x54
    Call Trace:
     fc_rport_final_delete+0xea/0x1d0 [scsi_transport_fc]
     process_one_work+0x1d3/0x390
     worker_thread+0x30/0x390

    Preceding kernel log message:
     lpfc_rport_invalid: Null vport on ndlp xffff9c36d412bc00

  Add a call to lpfc_rport_invalid() at the start of
  lpfc_dev_loss_tmo_callbk() to validate all required pointers before
  dereferencing them, consistent with lpfc_terminate_rport_io().

Signed-off-by: Vaibhav Nagare <vnagare@redhat.com>
---
 drivers/scsi/lpfc/lpfc_hbadisc.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c b/drivers/scsi/lpfc/lpfc_hbadisc.c
index b8649c40b537..af56c32708c6 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -163,27 +163,15 @@ lpfc_dev_loss_tmo_callbk(struct fc_rport *rport)
 	unsigned long iflags;
 	bool drop_initial_node_ref = false;
 
+	/* Validate rport, rdata, ndlp, and vport before proceeding */
+	if (lpfc_rport_invalid(rport))
+		return;
+
 	ndlp = ((struct lpfc_rport_data *)rport->dd_data)->pnode;
 	if (!ndlp)
 		return;
 
 	vport = ndlp->vport;
-	if (!vport) {
-		/*
-		 * Vport is NULL - this can happen during teardown when the
-		 * vport has been destroyed but the rport final delete is
-		 * still processing. Clear the association and return.
-		 */
-		pr_err("lpfc: Null vport on ndlp %p, DID x%06x rport %p\n",
-		       ndlp, ndlp->nlp_DID, rport);
-
-		spin_lock_irqsave(&ndlp->lock, iflags);
-		((struct lpfc_rport_data *)rport->dd_data)->pnode = NULL;
-		ndlp->rport = NULL;
-		spin_unlock_irqrestore(&ndlp->lock, iflags);
-		return;
-	}
-
 	phba  = vport->phba;
 
 	lpfc_debugfs_disc_trc(vport, LPFC_DISC_TRC_RPORT,
-- 
2.54.0