netfilter: ipset: add missing range check in bitmap_ip_uadt

When tb[IPSET_ATTR_IP_TO] is not present but tb[IPSET_ATTR_CIDR] exists,
the values of ip and ip_to are slightly swapped. Therefore, the range check
for ip should be done later, but this part is missing and it seems that the
vulnerability occurs.

So we should add missing range checks and remove unnecessary range checks.

Cc: <[e-mail]>
Reported-by: [e-mail]
Fixes: 72205fc68bd1 ("netfilter: ipset: bitmap:ip set type support")
Signed-off-by: Jeongjun Park <[e-mail]>
Acked-by: Jozsef Kadlecsik <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/ipset/ip_set_bitmap_ip.c

···
 		ret = ip_set_get_hostipaddr4(tb[IPSET_ATTR_IP_TO], &ip_to);
 		if (ret)
 			return ret;
-		if (ip > ip_to) {
+		if (ip > ip_to)
 			swap(ip, ip_to);
-			if (ip < map->first_ip)
-				return -IPSET_ERR_BITMAP_RANGE;
-		}
 	} else if (tb[IPSET_ATTR_CIDR]) {
 		u8 cidr = nla_get_u8(tb[IPSET_ATTR_CIDR]);
 
···
 		ip_to = ip;
 	}
 
-	if (ip_to > map->last_ip)
+	if (ip < map->first_ip || ip_to > map->last_ip)
 		return -IPSET_ERR_BITMAP_RANGE;
 
 	for (; !before(ip_to, ip); ip += map->hosts) {