From: "Ewan D. Milne" <emilne@redhat.com>
Date: Wed, 29 Jul 2020 19:10:11 -0400
Subject: scsi: lpfc: nvmet: Avoid hang / use-after-free again when destroying
 targetport
Patch-mainline: v5.9-rc1
Git-commit: af6de8c60fe9433afa73cea6fcccdccd98ad3e5e
References: bsc#1171558 bsc#1136666

We cannot wait on a completion object in the lpfc_nvme_targetport structure
in the _destroy_targetport() code path because the NVMe/fc transport will
free that structure immediately after the .targetport_delete() callback.
This results in a use-after-free, and a crash if slub_debug=FZPU is
enabled.

An earlier fix put put the completion on the stack, but commit 2a0fb340fcc8
("scsi: lpfc: Correct localport timeout duration error") subsequently
changed the code to reference the completion through a pointer in the
object rather than the local stack variable.  Fix this by using the stack
variable directly.

Link: https://lore.kernel.org/r/20200729231011.13240-1-emilne@redhat.com
Fixes: 2a0fb340fcc8 ("scsi: lpfc: Correct localport timeout duration error")
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/scsi/lpfc/lpfc_nvmet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -1886,7 +1886,7 @@ lpfc_nvmet_destroy_targetport(struct lpf
 		}
 		tgtp->tport_unreg_cmp = &tport_unreg_cmp;
 		nvmet_fc_unregister_targetport(phba->targetport);
-		if (!wait_for_completion_timeout(tgtp->tport_unreg_cmp,
+		if (!wait_for_completion_timeout(&tport_unreg_cmp,
 					msecs_to_jiffies(LPFC_NVMET_WAIT_TMO)))
 			lpfc_printf_log(phba, KERN_ERR, LOG_NVME,
 					"6179 Unreg targetport %p timeout "