l2tp: Fix locking in l2tp_core.c (6af88da1) · Commits · 戴 / test

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:

David S. Miller <davem@davemloft.net>

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;

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