Guard SIOCDELMULTI if_ioctl calls with KERNEL_LOCK() where the call is

made from socket close path. Most device drivers are not MP-safe yet,
and the closing of AF_INET and AF_INET6 sockets is no longer under the
kernel lock.

This fixes a panic seen by jcs@.

OK mpi@

sys/netinet/in.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: in.c,v 1.168 2019/12/01 21:12:42 jca Exp $	*/
+/*	$OpenBSD: in.c,v 1.169 2020/03/15 05:34:13 visa Exp $	*/
 /*	$NetBSD: in.c,v 1.26 1996/02/13 23:41:39 christos Exp $	*/
 
 /*
@@ -929,7 +929,9 @@ in_delmulti(struct in_multi *inm)
 			    sizeof(struct sockaddr_in);
 			satosin(&ifr.ifr_addr)->sin_family = AF_INET;
 			satosin(&ifr.ifr_addr)->sin_addr = inm->inm_addr;
+			KERNEL_LOCK();
 			(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
+			KERNEL_UNLOCK();
 
 			TAILQ_REMOVE(&ifp->if_maddrlist, &inm->inm_ifma,
 			    ifma_list);

sys/netinet/ip_mroute.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_mroute.c,v 1.128 2019/09/02 13:12:09 bluhm Exp $	*/
+/*	$OpenBSD: ip_mroute.c,v 1.129 2020/03/15 05:34:13 visa Exp $	*/
 /*	$NetBSD: ip_mroute.c,v 1.85 2004/04/26 01:31:57 matt Exp $	*/
 
 /*
@@ -772,7 +772,9 @@ vif_delete(struct ifnet *ifp)
 	satosin(&ifr.ifr_addr)->sin_len = sizeof(struct sockaddr_in);
 	satosin(&ifr.ifr_addr)->sin_family = AF_INET;
 	satosin(&ifr.ifr_addr)->sin_addr = zeroin_addr;
+	KERNEL_LOCK();
 	(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
+	KERNEL_UNLOCK();
 
 	free(v, M_MRTABLE, sizeof(*v));
 }

sys/netinet6/in6.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: in6.c,v 1.234 2019/11/18 22:08:59 bluhm Exp $	*/
+/*	$OpenBSD: in6.c,v 1.235 2020/03/15 05:34:14 visa Exp $	*/
 /*	$KAME: in6.c,v 1.372 2004/06/14 08:14:21 itojun Exp $	*/
 
 /*
@@ -1100,7 +1100,9 @@ in6_delmulti(struct in6_multi *in6m)
 			ifr.ifr_addr.sin6_len = sizeof(struct sockaddr_in6);
 			ifr.ifr_addr.sin6_family = AF_INET6;
 			ifr.ifr_addr.sin6_addr = in6m->in6m_addr;
+			KERNEL_LOCK();
 			(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
+			KERNEL_UNLOCK();
 
 			TAILQ_REMOVE(&ifp->if_maddrlist, &in6m->in6m_ifma,
 			    ifma_list);

sys/netinet6/ip6_mroute.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_mroute.c,v 1.122 2019/09/04 16:13:49 bluhm Exp $	*/
+/*	$OpenBSD: ip6_mroute.c,v 1.123 2020/03/15 05:34:14 visa Exp $	*/
 /*	$NetBSD: ip6_mroute.c,v 1.59 2003/12/10 09:28:38 itojun Exp $	*/
 /*	$KAME: ip6_mroute.c,v 1.45 2001/03/25 08:38:51 itojun Exp $	*/
 
@@ -565,7 +565,9 @@ ip6_mrouter_detach(struct ifnet *ifp)
 	memset(&ifr, 0, sizeof(ifr));
 	ifr.ifr_addr.sin6_family = AF_INET6;
 	ifr.ifr_addr.sin6_addr = in6addr_any;
+	KERNEL_LOCK();
 	(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
+	KERNEL_UNLOCK();
 
 	free(m6, M_MRTABLE, sizeof(*m6));
 }