netfilter: nf_tables: NULL pointer dereference in nf_tables_updobj()

static analyzer detect null pointer dereference case for 'type'
function __nft_obj_type_get() can return NULL value which require to handle
if type is NULL pointer return -ENOENT.

This is a theoretical issue, since an existing object has a type, but
better add this failsafe check.
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -7023,6 +7023,9 @@ static int nf_tables_newobj(struct sk_buff *skb, const struct nfnl_info *info,
 			return -EOPNOTSUPP;
 
 		type = __nft_obj_type_get(objtype);
+		if (WARN_ON_ONCE(!type))
+			return -ENOENT;
+
 		nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
 
 		return nf_tables_updobj(&ctx, type, nla[NFTA_OBJ_DATA], obj);