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Commit 6af88da1 authored by David S. Miller's avatar David S. Miller
Browse files

l2tp: Fix locking in l2tp_core.c 



l2tp_xmit_skb() must take the socket lock.  It makes use of ip_queue_xmit()
which expects to execute in a socket atomic context.

Since we execute this function in software interrupts, we cannot use the
usual lock_sock()/release_sock() sequence, instead we have to use
bh_lock_sock() and see if a user has the socket locked, and if so drop
the packet.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2f16270f

net/l2tp/l2tp_core.c

+8 −0
Original line number Diff line number Diff line
@@ -1060,6 +1060,12 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len 
			      IPSKB_REROUTED);

	nf_reset(skb);



	bh_lock_sock(sk);

	if (sock_owned_by_user(sk)) {

		dev_kfree_skb(skb);

		goto out_unlock;

	}



	/* Get routing info from the tunnel socket */

	skb_dst_drop(skb);

	skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
@@ -1106,6 +1112,8 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len 
	l2tp_skb_set_owner_w(skb, sk);



	l2tp_xmit_core(session, skb, data_len);

out_unlock:

	bh_unlock_sock(sk);



abort:

	return 0;