4.14-stable review patch.  If anyone has any objections, please let me know.


From: Julian Wiedmann <j...@linux.vnet.ibm.com>

[ Upstream commit 14d066c3531a87f727968cacd85bd95c75f59843 ]

Registering an IPv4 address with the HW takes quite a while, so we
temporarily drop the ip_htable lock. Any concurrent add/remove of the
same IP adjusts the IP's use count, and (on remove) is then blocked by
After the register call has completed, we check the use count for
concurrently attempted add/remove calls - and possibly straight-away
deregister the IP again. This happens via l3_delete_ip(), which
1) looks up the queried IP in the htable (getting a reference to the
   *same* queried object),
2) deregisters the IP from the HW, and
3) frees the IP object.

The caller in l3_add_ip() then does a second free on the same object.

For this case, skip all the extra checks and lookups in l3_delete_ip()
and just deregister & free the IP object ourselves.

Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
Signed-off-by: Julian Wiedmann <j...@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
 drivers/s390/net/qeth_l3_main.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -319,7 +319,8 @@ int qeth_l3_add_ip(struct qeth_card *car
                                (rc == IPA_RC_LAN_OFFLINE)) {
                        addr->disp_flag = QETH_DISP_ADDR_DO_NOTHING;
                        if (addr->ref_counter < 1) {
-                               qeth_l3_delete_ip(card, addr);
+                               qeth_l3_deregister_addr_entry(card, addr);
+                               hash_del(&addr->hnode);
                } else {

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