ipv6/dccp: do not inherit ipv6_mc_list from parent

Like commit 657831ff ("dccp/tcp: do not inherit mc_list from parent")
we should clear ipv6_mc_list etc. for IPv6 sockets too.

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

CVE-2017-9076
CVE-2017-9077

(cherry-picked from 83eaddab)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

net/dccp/ipv6.c

@@ -422,6 +422,9 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
 		newsk->sk_backlog_rcv = dccp_v4_do_rcv;
 		newnp->pktoptions  = NULL;
 		newnp->opt	   = NULL;
+		newnp->ipv6_mc_list = NULL;
+		newnp->ipv6_ac_list = NULL;
+		newnp->ipv6_fl_list = NULL;
 		newnp->mcast_oif   = inet6_iif(skb);
 		newnp->mcast_hops  = ipv6_hdr(skb)->hop_limit;
 
@@ -486,6 +489,9 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
 	/* Clone RX bits */
 	newnp->rxopt.all = np->rxopt.all;
 
+	newnp->ipv6_mc_list = NULL;
+	newnp->ipv6_ac_list = NULL;
+	newnp->ipv6_fl_list = NULL;
 	newnp->pktoptions = NULL;
 	newnp->opt	  = NULL;
 	newnp->mcast_oif  = inet6_iif(skb);

net/ipv6/tcp_ipv6.c

@@ -1033,6 +1033,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 		newtp->af_specific = &tcp_sock_ipv6_mapped_specific;
 #endif
 
+		newnp->ipv6_mc_list = NULL;
 		newnp->ipv6_ac_list = NULL;
 		newnp->ipv6_fl_list = NULL;
 		newnp->pktoptions  = NULL;
@@ -1102,6 +1103,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 	   First: no IPv4 options.
 	 */
 	newinet->inet_opt = NULL;
+	newnp->ipv6_mc_list = NULL;
 	newnp->ipv6_ac_list = NULL;
 	newnp->ipv6_fl_list = NULL;