Fix kernel panic while trying to read multicast stream.

When VIMAGE is enabled make sure the "m_pkthdr.rcvif" pointer is set
for all mbufs being input by the IGMP/MLD6 code. Else there will be a
NULL-pointer dereference in the netisr code when trying to set the
VNET based on the incoming mbuf. Add an assert to catch this when
queueing mbufs on a netisr to make debugging of similar cases easier.

Found by:	Vladislav V. Prodan
PR:		244002
Reviewed by:	bz@
MFC after:	1 week
Sponsored by:	Mellanox Technologies

sys/net/netisr.c

@@ -1056,6 +1056,8 @@ netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m)
 	if (m != NULL) {
 		KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__,
 		    cpuid));
+		VNET_ASSERT(m->m_pkthdr.rcvif != NULL,
+		    ("%s:%d rcvif == NULL: m=%p", __func__, __LINE__, m));
 		error = netisr_queue_internal(proto, m, cpuid);
 	} else
 		error = ENOBUFS;

sys/netinet/igmp.c

@@ -303,6 +303,7 @@ igmp_save_context(struct mbuf *m, struct ifnet *ifp)
 #ifdef VIMAGE
 	m->m_pkthdr.PH_loc.ptr = ifp->if_vnet;
 #endif /* VIMAGE */
+	m->m_pkthdr.rcvif = ifp;
 	m->m_pkthdr.flowid = ifp->if_index;
 }
 

sys/netinet6/mld6.c

@@ -283,6 +283,7 @@ mld_save_context(struct mbuf *m, struct ifnet *ifp)
 #ifdef VIMAGE
 	m->m_pkthdr.PH_loc.ptr = ifp->if_vnet;
 #endif /* VIMAGE */
+	m->m_pkthdr.rcvif = ifp;
 	m->m_pkthdr.flowid = ifp->if_index;
 }