From 6afe56f9c3acf521f9896cd2a546ce870d9e3a6c Mon Sep 17 00:00:00 2001
From: Ryan Libby <rlibby@FreeBSD.org>
Date: Mon, 25 Nov 2019 22:25:10 +0000
Subject: [PATCH] in6_joingroup_locked: need if_addr_lock around
 in6m_disconnect_locked

It looks like the call that requires the lock was introduced in r337866.

Reviewed by:	hselasky
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D20739
---
 sys/netinet6/in6_mcast.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/netinet6/in6_mcast.c b/sys/netinet6/in6_mcast.c
index 5e7969d2a6da..ec33273144db 100644
--- a/sys/netinet6/in6_mcast.c
+++ b/sys/netinet6/in6_mcast.c
@@ -1267,6 +1267,7 @@ in6_joingroup_locked(struct ifnet *ifp, const struct in6_addr *mcaddr,
 		struct epoch_tracker et;
 
 		CTR2(KTR_MLD, "%s: dropping ref on %p", __func__, inm);
+		IF_ADDR_WLOCK(ifp);
 		NET_EPOCH_ENTER(et);
 		CK_STAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
 			if (ifma->ifma_protospec == inm) {
@@ -1277,6 +1278,7 @@ in6_joingroup_locked(struct ifnet *ifp, const struct in6_addr *mcaddr,
 		in6m_disconnect_locked(&inmh, inm);
 		in6m_rele_locked(&inmh, inm);
 		NET_EPOCH_EXIT(et);
+		IF_ADDR_WUNLOCK(ifp);
 	} else {
 		*pinm = inm;
 	}