tipc: fix possible crash in __tipc_nl_net_set()

syzbot reported a crash in __tipc_nl_net_set() caused by NULL dereference.

We need to check that both TIPC_NLA_NET_NODEID and TIPC_NLA_NET_NODEID_W1
are present.

We also need to make sure userland provided u64 attributes.

Fixes: d50ccc2d3909 ("tipc: add 128-bit node identifier")
Signed-off-by: Eric Dumazet <[e-mail]>
Cc: Jon Maloy <[e-mail]>
Cc: Ying Xue <[e-mail]>
Reported-by: syzbot <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/tipc/net.c

···
 		u64 *w0 = (u64 *)&node_id[0];
 		u64 *w1 = (u64 *)&node_id[8];
 
+		if (!attrs[TIPC_NLA_NET_NODEID_W1])
+			return -EINVAL;
 		*w0 = nla_get_u64(attrs[TIPC_NLA_NET_NODEID]);
 		*w1 = nla_get_u64(attrs[TIPC_NLA_NET_NODEID_W1]);
 		tipc_net_init(net, node_id, 0);

net/tipc/netlink.c

···
 	[TIPC_NLA_NET_UNSPEC]		= { .type = NLA_UNSPEC },
 	[TIPC_NLA_NET_ID]		= { .type = NLA_U32 },
 	[TIPC_NLA_NET_ADDR]		= { .type = NLA_U32 },
+	[TIPC_NLA_NET_NODEID]		= { .type = NLA_U64 },
+	[TIPC_NLA_NET_NODEID_W1]	= { .type = NLA_U64 },
 };
 
 const struct nla_policy tipc_nl_link_policy[TIPC_NLA_LINK_MAX + 1] = {