[PATCH AUTOSEL 4.20 51/77] scsi: lpfc: nvme: avoid hang / use-after-free when destroying localport

Sasha Levin
2019-02-15T02:38:48Z

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

[ Upstream commit 7961cba6f7d8215fa632df3d220e5154bb825249 ]

We cannot wait on a completion object in the lpfc_nvme_lport structure in
the _destroy_localport() code path because the NVMe/fc transport will free
that structure immediately after the .localport_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_nvme.c | 16 +++++++++-------
drivers/scsi/lpfc/lpfc_nvme.h | 2 +-
2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_nvme.c b/drivers/scsi/lpfc/lpfc_nvme.c
index ba831def9301..b6fe88de372a 100644
--- a/drivers/scsi/lpfc/lpfc_nvme.c
+++ b/drivers/scsi/lpfc/lpfc_nvme.c
@@ -297,7 +297,8 @@ lpfc_nvme_localport_delete(struct nvme_fc_local_port *localport)
lport);

/* release any threads waiting for the unreg to complete */
- complete(&lport->lport_unreg_done);
+ if (lport->vport->localport)
+ complete(lport->lport_unreg_cmp);
}

/* lpfc_nvme_remoteport_delete
@@ -2547,7 +2548,8 @@ lpfc_nvme_create_localport(struct lpfc_vport *vport)
*/
void
lpfc_nvme_lport_unreg_wait(struct lpfc_vport *vport,
- struct lpfc_nvme_lport *lport)
+ struct lpfc_nvme_lport *lport,
+ struct completion *lport_unreg_cmp)
{
#if (IS_ENABLED(CONFIG_NVME_FC))
u32 wait_tmo;
@@ -2559,8 +2561,7 @@ lpfc_nvme_lport_unreg_wait(struct lpfc_vport *vport,
*/
wait_tmo = msecs_to_jiffies(LPFC_NVME_WAIT_TMO * 1000);
while (true) {
- ret = wait_for_completion_timeout(&lport->lport_unreg_done,
- wait_tmo);
+ ret = wait_for_completion_timeout(lport_unreg_cmp, wait_tmo);
if (unlikely(!ret)) {
lpfc_printf_vlog(vport, KERN_ERR, LOG_NVME_IOERR,
"6176 Lport %p Localport %p wait "
@@ -2594,12 +2595,12 @@ lpfc_nvme_destroy_localport(struct lpfc_vport *vport)
struct lpfc_nvme_lport *lport;
struct lpfc_nvme_ctrl_stat *cstat;
int ret;
+ DECLARE_COMPLETION_ONSTACK(lport_unreg_cmp);

if (vport->nvmei_support == 0)
return;

localport = vport->localport;
- vport->localport = NULL;
lport = (struct lpfc_nvme_lport *)localport->private;
cstat = lport->cstat;

@@ -2610,13 +2611,14 @@ lpfc_nvme_destroy_localport(struct lpfc_vport *vport)
/* lport's rport list is clear. Unregister
* lport and release resources.
*/
- init_completion(&lport->lport_unreg_done);
+ lport->lport_unreg_cmp = &lport_unreg_cmp;
ret = nvme_fc_unregister_localport(localport);

/* Wait for completion. This either blocks
* indefinitely or succeeds
*/
- lpfc_nvme_lport_unreg_wait(vport, lport);
+ lpfc_nvme_lport_unreg_wait(vport, lport, &lport_unreg_cmp);
+ vport->localport = NULL;
kfree(cstat);

/* Regardless of the unregister upcall response, clear
diff --git a/drivers/scsi/lpfc/lpfc_nvme.h b/drivers/scsi/lpfc/lpfc_nvme.h
index cfd4719be25c..b234d0298994 100644
--- a/drivers/scsi/lpfc/lpfc_nvme.h
+++ b/drivers/scsi/lpfc/lpfc_nvme.h
@@ -50,7 +50,7 @@ struct lpfc_nvme_ctrl_stat {
/* Declare nvme-based local and remote port definitions. */
struct lpfc_nvme_lport {
struct lpfc_vport *vport;
- struct completion lport_unreg_done;
+ struct completion *lport_unreg_cmp;
/* Add stats counters here */
struct lpfc_nvme_ctrl_stat *cstat;
atomic_t fc4NvmeLsRequests;
--
2.19.1