From d477a7feed177d0ad5c12bc6e2cce804d427ed38 Mon Sep 17 00:00:00 2001
From: "Andrey V. Elsukov" <ae@FreeBSD.org>
Date: Thu, 5 Aug 2021 11:51:46 +0300
Subject: [PATCH] Fix panic in IPv6 multicast code.

Add check that ifp supports IPv6 multicasts in in6_getmulti.
This fixes panic when user application tries to join into multicast
group on an interface that doesn't support IPv6 multicasts, like
IFT_PFLOG interfaces.

PR:             257302
Reviewed by:	melifaro
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D31420
---
 sys/netinet6/in6_mcast.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/sys/netinet6/in6_mcast.c b/sys/netinet6/in6_mcast.c
index 0744a1178fc..7326befc6d0 100644
--- a/sys/netinet6/in6_mcast.c
+++ b/sys/netinet6/in6_mcast.c
@@ -374,9 +374,18 @@ in6_getmulti(struct ifnet *ifp, const struct in6_addr *group,
 	IN6_MULTI_LIST_LOCK();
 	IF_ADDR_WLOCK(ifp);
 	NET_EPOCH_ENTER(et);
-	inm = in6m_lookup_locked(ifp, group);
+	/*
+	 * Does ifp support IPv6 multicasts?
+	 */
+	if (ifp->if_afdata[AF_INET6] == NULL)
+		error = ENODEV;
+	else
+		inm = in6m_lookup_locked(ifp, group);
 	NET_EPOCH_EXIT(et);
 
+	if (error != 0)
+		goto out_locked;
+
 	if (inm != NULL) {
 		/*
 		 * If we already joined this group, just bump the