scsi: lpfc: nvmet: Avoid hang / use-after-free again when destroying targetport

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>

diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index a4430ae..d4ade7c 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -2110,7 +2110,7 @@ lpfc_nvmet_destroy_targetport(struct lpfc_hba *phba)
                }
                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_TRACE_EVENT,
                                        "6179 Unreg targetport x%px timeout "