nvmet-fc: fix issues with targetport assoc_list list walking

There are two changes:

1) The logic in the __nvmet_fc_free_assoc() routine is bad. It uses
"safe" routines assuming pointers will come back valid.  However, the
intervening next structure being linked can be removed from the list and
the resulting safe pointers are bad, resulting in NULL ptrs being hit.

Correct by scheduling a work element to perform the association delete,
which can be done while under lock.

2) Prior patch that added the work element scheduling left a possible
reference on the object if the work element couldn't be scheduled.

Correct by doing the put on a failing schedule_work() call.

Signed-off-by: Nigel Kirkland <nigel.kirkland@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 1e9654f04c608d194bb464b854180ed1b0c06ef9..6b7bbf39fa067d369e9f8acd8db2dbb5be488b2e 100644 (file)
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -1143,10 +1143,8 @@ __nvmet_fc_free_assocs(struct nvmet_fc_tgtport *tgtport)
                                &tgtport->assoc_list, a_list) {
                if (!nvmet_fc_tgt_a_get(assoc))
                        continue;
-               spin_unlock_irqrestore(&tgtport->lock, flags);
-               nvmet_fc_delete_target_assoc(assoc);
-               nvmet_fc_tgt_a_put(assoc);
-               spin_lock_irqsave(&tgtport->lock, flags);
+               if (!schedule_work(&assoc->del_work))
+                       nvmet_fc_tgt_a_put(assoc);
        }
        spin_unlock_irqrestore(&tgtport->lock, flags);
 }
@@ -1185,7 +1183,8 @@ nvmet_fc_delete_ctrl(struct nvmet_ctrl *ctrl)
                nvmet_fc_tgtport_put(tgtport);
 
                if (found_ctrl) {
-                       schedule_work(&assoc->del_work);
+                       if (!schedule_work(&assoc->del_work))
+                               nvmet_fc_tgt_a_put(assoc);
                        return;
                }