Task already implemented:

@c-po The above commits should reference T1556, probably a typo.

When I compiled it without --static everything went well.

Daniil, Yuriy, plz watch on it, may be you got any ideas?

Vladislav thinks that the bug is not in Zabbix. On the one hand, I agree with him, because early (on early version of VyOS 1.2 at summer, autumn) it works perfectly...
But test app that he made for me works ok, without crashes... So i dont know what to do... Any ideas?

for example it crashing when in config from server there is a discovery rule with network like 192.168.1.0/24, early, before we patched it and remove gethostbyaddr conversion, it crashes when agent connects to it...
So it's look like all depend from ip addresses and may be gethostbyaddr....

Nope. The function gethostbyaddr() is a libc function. What you can do is to try to reproduce the issue under debian 8 (jessie).
The crash in the zabbix ticket however is that the zabbix proxy is crashing when it received 3123 byte from 10.255.0.1.

Could it be connected? https://phabricator.vyos.net/T1214

I have removed resolving of IP address into DNS, you can also try compiling with --enable-ipv6 flag to use different functions in order to avoid this issue.
Can you please provide a little bit more information about you system ? It is very strange that gethostbyaddr() function crash, have you tried updating your system to latest version ?

looks to me like a classic buffer overflow on the zabix agent.

no ideas?