802: fix a possible race condition
(Resend with a better changelog)
garp_pdu_queue() should ways be called with this spin lock.
garp_uninit_applicant() only holds rtnl lock which is not
enough here. A possible race can happen as garp_pdu_rcv()
is called in BH context:
garp_pdu_rcv()
|->garp_pdu_parse_msg()
|->garp_pdu_parse_attr()
|-> garp_gid_event()
Found by code inspection.
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: David Ward <david.ward@ll.mit.edu>
Cc: "Jorge Boncompte [DTI2]" <jorge@dti2.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/802/garp.c b/net/802/garp.c
index 8456f5d..5d9630a 100644
--- a/net/802/garp.c
+++ b/net/802/garp.c
@@ -609,8 +609,12 @@
/* Delete timer and generate a final TRANSMIT_PDU event to flush out
* all pending messages before the applicant is gone. */
del_timer_sync(&app->join_timer);
+
+ spin_lock_bh(&app->lock);
garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
garp_pdu_queue(app);
+ spin_unlock_bh(&app->lock);
+
garp_queue_xmit(app);
dev_mc_del(dev, appl->proto.group_address);