From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: conclude all event processing before offlining a card
Patch-mainline: v5.0-rc6
Git-commit: c0a2e4d10d9366ada133a8ae4ff2f32397f8b15b
References: LTC#175901, bsc#1127567 

Description:   qeth: conclude all event processing before offlining a card
Symptom:       Undefined behaviour when a qeth device is in Bridgeport mode
               and eligible to receive associated events
               (Address Change Notifications, State Change Notifications).
Problem:       Work for Bridgeport events is currently placed on a
               driver-wide workqueue. If the card is removed and freed while
               any such work is still active, this causes a use-after-free.
Solution:      Put the events on a per-card queue, where we can control
               their lifetime. As we also don't want stale events to last
               beyond an offline & online cycle, flush this queue when
               setting the card offline.
Reproduction:  -

Upstream-Description:

              s390/qeth: conclude all event processing before offlining a card

              Work for Bridgeport events is currently placed on a driver-wide
              workqueue. If the card is removed and freed while any such work is still
              active, this causes a use-after-free.
              So put the events on a per-card queue, where we can control their
              lifetime. As we also don't want stale events to last beyond an
              offline & online cycle, flush this queue when setting the card offline.

              Fixes: b4d72c08b358 ("qeth: bridgeport support - basic control")
              Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
              Signed-off-by: David S. Miller <davem@davemloft.net>


Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Denis Kirjanov <dkirjanov@suse.com>
---
 drivers/s390/net/qeth_core.h      |    2 +-
 drivers/s390/net/qeth_core_main.c |   10 ++++++++--
 drivers/s390/net/qeth_l2_main.c   |    6 ++++--
 drivers/s390/net/qeth_l3_main.c   |    2 ++
 4 files changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -790,6 +790,7 @@ struct qeth_card {
 	struct qeth_seqno seqno;
 	struct qeth_card_options options;
 
+	struct workqueue_struct *event_wq;
 	wait_queue_head_t wait_q;
 	spinlock_t mclock;
 	unsigned long active_vlans[BITS_TO_LONGS(VLAN_N_VID)];
@@ -968,7 +969,6 @@ extern const struct attribute_group *qet
 extern const struct attribute_group qeth_device_attr_group;
 extern const struct attribute_group qeth_device_blkt_group;
 extern const struct device_type qeth_generic_devtype;
-extern struct workqueue_struct *qeth_wq;
 
 int qeth_card_hw_is_reachable(struct qeth_card *);
 const char *qeth_get_cardname_short(struct qeth_card *);
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -75,8 +75,7 @@ static void qeth_notify_skbs(struct qeth
 static void qeth_release_skbs(struct qeth_qdio_out_buffer *buf);
 static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *, int);
 
-struct workqueue_struct *qeth_wq;
-EXPORT_SYMBOL_GPL(qeth_wq);
+static struct workqueue_struct *qeth_wq;
 
 int qeth_card_hw_is_reachable(struct qeth_card *card)
 {
@@ -1466,6 +1465,10 @@ static struct qeth_card *qeth_alloc_card
 	CARD_RDEV(card) = gdev->cdev[0];
 	CARD_WDEV(card) = gdev->cdev[1];
 	CARD_DDEV(card) = gdev->cdev[2];
+
+	card->event_wq = alloc_ordered_workqueue("%s", 0, dev_name(&gdev->dev));
+	if (!card->event_wq)
+		goto out_wq;
 	if (qeth_setup_channel(&card->read, true))
 		goto out_ip;
 	if (qeth_setup_channel(&card->write, true))
@@ -1481,6 +1484,8 @@ out_data:
 out_channel:
 	qeth_clean_channel(&card->read);
 out_ip:
+	destroy_workqueue(card->event_wq);
+out_wq:
 	dev_set_drvdata(&gdev->dev, NULL);
 	kfree(card);
 out:
@@ -5028,6 +5033,7 @@ static void qeth_core_free_card(struct q
 	qeth_clean_channel(&card->read);
 	qeth_clean_channel(&card->write);
 	qeth_clean_channel(&card->data);
+	destroy_workqueue(card->event_wq);
 	qeth_free_qdio_buffers(card);
 	unregister_service_level(&card->qeth_service_level);
 	dev_set_drvdata(&card->gdev->dev, NULL);
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -391,6 +391,8 @@ static void qeth_l2_stop_card(struct qet
 		qeth_clear_cmd_buffers(&card->read);
 		qeth_clear_cmd_buffers(&card->write);
 	}
+
+	flush_workqueue(card->event_wq);
 }
 
 static int qeth_l2_process_inbound_buffer(struct qeth_card *card,
@@ -1455,7 +1457,7 @@ static void qeth_bridge_state_change(str
 	data->card = card;
 	memcpy(&data->qports, qports,
 			sizeof(struct qeth_sbp_state_change) + extrasize);
-	queue_work(qeth_wq, &data->worker);
+	queue_work(card->event_wq, &data->worker);
 }
 
 struct qeth_bridge_host_data {
@@ -1527,7 +1529,7 @@ static void qeth_bridge_host_event(struc
 	data->card = card;
 	memcpy(&data->hostevs, hostevs,
 			sizeof(struct qeth_ipacmd_addr_change) + extrasize);
-	queue_work(qeth_wq, &data->worker);
+	queue_work(card->event_wq, &data->worker);
 }
 
 /* SETBRIDGEPORT support; sending commands */
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1436,6 +1436,8 @@ static void qeth_l3_stop_card(struct qet
 		qeth_clear_cmd_buffers(&card->read);
 		qeth_clear_cmd_buffers(&card->write);
 	}
+
+	flush_workqueue(card->event_wq);
 }
 
 /*
