[PATCH AUTOSEL 4.20 52/77] scsi: lpfc: nvmet: avoid hang / use-after-free when destroying targetport

Sasha Levin
2019-02-15T02:38:46Z

From: "Ewan D. Milne" <emilne@redhat.com>

[ Upstream commit c41f59884be5cca293ed61f3d64637dbba3a6381 ]

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 hang if slub_debug=FZPU is enabled.

Fix this by putting the completion on the stack.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_nvmet.c | 8 +++++---
drivers/scsi/lpfc/lpfc_nvmet.h | 2 +-
2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index 6245f442d784..95fee83090eb 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -1003,7 +1003,8 @@ lpfc_nvmet_targetport_delete(struct nvmet_fc_target_port *targetport)
struct lpfc_nvmet_tgtport *tport = targetport->private;

/* release any threads waiting for the unreg to complete */
- complete(&tport->tport_unreg_done);
+ if (tport->phba->targetport)
+ complete(tport->tport_unreg_cmp);
}

static void
@@ -1692,6 +1693,7 @@ lpfc_nvmet_destroy_targetport(struct lpfc_hba *phba)
struct lpfc_nvmet_tgtport *tgtp;
struct lpfc_queue *wq;
uint32_t qidx;
+ DECLARE_COMPLETION_ONSTACK(tport_unreg_cmp);

if (phba->nvmet_support == 0)
return;
@@ -1701,9 +1703,9 @@ lpfc_nvmet_destroy_targetport(struct lpfc_hba *phba)
wq = phba->sli4_hba.nvme_wq[qidx];
lpfc_nvmet_wqfull_flush(phba, wq, NULL);
}
- init_completion(&tgtp->tport_unreg_done);
+ tgtp->tport_unreg_cmp = &tport_unreg_cmp;
nvmet_fc_unregister_targetport(phba->targetport);
- wait_for_completion_timeout(&tgtp->tport_unreg_done, 5);
+ wait_for_completion_timeout(&tport_unreg_cmp, 5);
lpfc_nvmet_cleanup_io_context(phba);
}
phba->targetport = NULL;
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.h b/drivers/scsi/lpfc/lpfc_nvmet.h
index 1aaff63f1f41..0ec1082ce7ef 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.h
+++ b/drivers/scsi/lpfc/lpfc_nvmet.h
@@ -34,7 +34,7 @@
/* Used for NVME Target */
struct lpfc_nvmet_tgtport {
struct lpfc_hba *phba;
- struct completion tport_unreg_done;
+ struct completion *tport_unreg_cmp;

/* Stats counters - lpfc_nvmet_unsol_ls_buffer */
atomic_t rcv_ls_req_in;
--
2.19.1