[dhcp_relay] dhcp6relay memory issue resulting in segfault

[kellyyeh]

Description

DHCPv6 Relay tests are failing on armhf with dhcp6relay resulting in segfault

Steps to reproduce the issue:

1. On version 20201231.48, 20201231.49, 20201231.50, run dhcpv6 relay management tests
2. Tests fail and dhcp6relay results in segfault

Describe the results you received:

// Initialization
Jan 23 20:52:00.690932 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === add config for intf Vlan1000
Jan 23 20:52:00.692032 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === associating config 0x16c59a8 intf Vlan1000 with db connector 0xbe834b3c

// a good relay
Jan 23 20:53:48.473310 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === callback updating #2 config 0x16c59a8 message type 1(0x1)
Jan 23 20:53:48.474304 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === send_udp updating #1 config 0x16c59a8 message type 12(0xc)

// some more good relays
Jan 23 20:53:53.065216 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: message repeated 3 times: [ === send_udp updating #1 config 0x16c59a8 message type 12(0xc)]

// This seems to be the problem. The config address changed (last byte got zeroed out):
Jan 23 20:53:53.065699 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === server_callback updating #3 config 0x16c59a8 message type 13(0xd)
Jan 23 20:53:53.066095 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === send_udp updating #1 config 0x16c5900 message type 2(0x2)

// crashed then restarted:
Jan 23 20:55:28.674247 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === add config for intf Vlan1000
Jan 23 20:55:28.674478 str2-7215-acs-3 WARNING dhcp_relay#dhcp6relay: === associating config 0x1a449a8 intf Vlan1000 with db connector 0xbe9dbb3c

Describe the results you expected:

Config address should stay the same upon receiving and sending packets.

Output of show version:

 

Docker images: 

REPOSITORY                 TAG                 IMAGE ID            SIZE 

docker-syncd-mrvl          20201231.50         1676bfbdc32c        546MB 

docker-syncd-mrvl          latest              1676bfbdc32c        546MB 

docker-snmp                20201231.50         f118fe3e753d        467MB 

docker-snmp                latest              f118fe3e753d        467MB 

docker-teamd               20201231.50         53102d8accb5        435MB 

docker-teamd               latest   a           53102d8accb5        435MB 

docker-router-advertiser   20201231.50         53399a5a0d79        428MB 

docker-router-advertiser   latest              53399a5a0d79        428MB 

docker-platform-monitor    20201231.50         271246a1b81e        561MB 

docker-platform-monitor    latest              271246a1b81e        561MB 

docker-lldp                20201231.50         ca98c2222f54        431MB 

docker-lldp                latest              ca98c2222f54        431MB 

docker-database            20201231.50         3993b75cb9ea        427MB 

docker-database            latest              3993b75cb9ea        427MB 

docker-acms                20201231.50         eead63234782        271MB 

docker-acms                latest              eead63234782        271MB 

docker-orchagent           20201231.50         82655245db79        521MB 

docker-orchagent           latest              82655245db79        521MB 

docker-dhcp-relay          20201231.50         ab80fabaccda        442MB 

docker-dhcp-relay          latest              ab80fabaccda        442MB 

docker-sonic-telemetry     20201231.50         39f65d822b30        504MB 

docker-sonic-telemetry     latest              39f65d822b30        504MB 

docker-fpm-frr             20201231.50         b0159c4cf554        447MB 

docker-fpm-frr             latest              b0159c4cf554        447MB 

docker-sflow               20201231.50         57493c04ad16        435MB 

docker-sflow               latest              57493c04ad16        435MB 

docker-mux                 20201231.50         b76a0fb8510c        446MB 

docker-mux                 latest              b76a0fb8510c        446MB 

k8s.gcr.io/pause           3.4.1               3f46e9d0aa60        325kB 

Output of show techsupport:

(paste your output here or download and attach the file here )

Additional information you deem important (e.g. issue happens only occasionally):