[PATCH 4.20 127/171] s390/qeth: cancel close_dev work before removing a card

Greg Kroah-Hartman
2019-03-12T17:13:54Z

[ Upstream commit c2780c1a3fb724560b1d44f7976e0de17bf153c7 ]

A card's close_dev work is scheduled on a driver-wide workqueue. If the
card is removed and freed while the work is still active, this causes a
use-after-free.
So make sure that the work is completed before freeing the card.

Fixes: 0f54761d167f ("qeth: Support VEPA mode")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/net/qeth_core.h | 1 +
drivers/s390/net/qeth_l2_main.c | 2 ++
drivers/s390/net/qeth_l3_main.c | 1 +
3 files changed, 4 insertions(+)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 99af1a0a3314..8999be74c545 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -22,6 +22,7 @@
#include <linux/hashtable.h>
#include <linux/ip.h>
#include <linux/refcount.h>
+#include <linux/workqueue.h>

#include <net/ipv6.h>
#include <net/if_inet6.h>
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 8d3601891c62..49fa09c67d49 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -823,6 +823,8 @@ static void qeth_l2_remove_device(struct ccwgroup_device *cgdev)

if (cgdev->state == CCWGROUP_ONLINE)
qeth_l2_set_offline(cgdev);
+
+ cancel_work_sync(&card->close_dev_work);
if (qeth_netdev_is_registered(card->dev))
unregister_netdev(card->dev);
}
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index f08b745c2007..d1bf55b5c8e1 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2428,6 +2428,7 @@ static void qeth_l3_remove_device(struct ccwgroup_device *cgdev)
if (cgdev->state == CCWGROUP_ONLINE)
qeth_l3_set_offline(cgdev);

+ cancel_work_sync(&card->close_dev_work);
if (qeth_netdev_is_registered(card->dev))
unregister_netdev(card->dev);
qeth_l3_clear_ip_htable(card, 0);
--
2.19.1