From 6af88da14ee284aaad6e4326da09a89191ab6165 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sun, 8 May 2011 13:45:20 -0700 Subject: [PATCH] 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: David S. Miller --- net/l2tp/l2tp_core.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index c64ce0a0bb03..78530299ae38 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -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; -- 2.11.0