From 6069a2c0bdada7b581c7c3ba8308c6dd672f27a1 Mon Sep 17 00:00:00 2001
From: Andrew Thompson <thompsa@FreeBSD.org>
Date: Thu, 7 Jul 2011 20:02:09 +0000
Subject: [PATCH] Grab the rlock before checking if our interface is enabled,
 it could be possible to hit a dead pointer when changing interfaces.

PR:		kern/156978
Submitted by:	Andrew Boyer
MFC after:	1 week
---
 sys/net/if_lagg.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sys/net/if_lagg.c b/sys/net/if_lagg.c
index 2548c65f4f3..d540966ab4c 100644
--- a/sys/net/if_lagg.c
+++ b/sys/net/if_lagg.c
@@ -1221,14 +1221,15 @@ lagg_input(struct ifnet *ifp, struct mbuf *m)
 	struct lagg_softc *sc = lp->lp_softc;
 	struct ifnet *scifp = sc->sc_ifp;
 
+	LAGG_RLOCK(sc);
 	if ((scifp->if_drv_flags & IFF_DRV_RUNNING) == 0 ||
 	    (lp->lp_flags & LAGG_PORT_DISABLED) ||
 	    sc->sc_proto == LAGG_PROTO_NONE) {
+		LAGG_RUNLOCK(sc);
 		m_freem(m);
 		return (NULL);
 	}
 
-	LAGG_RLOCK(sc);
 	ETHER_BPF_MTAP(scifp, m);
 
 	m = (*sc->sc_input)(sc, lp, m);