scsi: elx: libefc: Fix potential use after free in efc_nport_vport_del()

The kref_put() function will call nport->release if the refcount drops to
zero.  The nport->release release function is _efc_nport_free() which frees
"nport".  But then we dereference "nport" on the next line which is a use
after free.  Re-order these lines to avoid the use after free.

Fixes: fcd427303eb9 ("scsi: elx: libefc: SLI and FC PORT state machine interfaces")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/b666ab26-6581-4213-9a3d-32a9147f0399@stanley.mountain
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/elx/libefc/efc_nport.c b/drivers/scsi/elx/libefc/efc_nport.c
index 2e83a667901fecda06be1a7d88f8c8d4bf381282..1a7437f4328e87eb10b67a5247a1c9bcdf9c5b46 100644 (file)
--- a/drivers/scsi/elx/libefc/efc_nport.c
+++ b/drivers/scsi/elx/libefc/efc_nport.c
@@ -705,9 +705,9 @@ efc_nport_vport_del(struct efc *efc, struct efc_domain *domain,
        spin_lock_irqsave(&efc->lock, flags);
        list_for_each_entry(nport, &domain->nport_list, list_entry) {
                if (nport->wwpn == wwpn && nport->wwnn == wwnn) {
-                       kref_put(&nport->ref, nport->release);
                        /* Shutdown this NPORT */
                        efc_sm_post_event(&nport->sm, EFC_EVT_SHUTDOWN, NULL);
+                       kref_put(&nport->ref, nport->release);
                        break;
                }
        }