Commit cfbe800b authored Apr 02, 2013 by Cong Wang Committed by David S. Miller Apr 07, 2013

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>

parent 23a95442

net/802/garp.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -609,8 +609,12 @@ void garp_uninit_applicant(struct net_device dev, struct garp_application appl
		/* 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);

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