double free crash, with snmp_sess_timeout

Hi,

I am using netsnmp 5.8, and facing double free crash on
snmp_synch_response, while trying to send snmp inform packets. Crash
is happening in snmp_sess_timeout, while trying to free varbinds.

gdb) bt
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1 0x0000ffffad811f54 in __GI_abort () at abort.c:79
#2 0x0000ffffad85c274 in __libc_message (action=action@entry=do_abort,
fmt=fmt@entry=0xffffad914a68 "%s\n")
at ../sysdeps/posix/libc_fatal.c:181
#3 0x0000ffffad86352c in malloc_printerr (str=str@entry=0xffffad9104f0
"double free or corruption (!prev)") at malloc.c:5332
#4 0x0000ffffad8650d0 in _int_free (av=0xffffa8000020,
p=0xffffa8007de0, have_lock=) at malloc.c:4317
#5 0x0000ffffada30834 in snmp_free_varbind (var=) at snmp_api.c:5800
#6 0x0000ffffada34bf8 in snmp_free_pdu (pdu=0xffffa80133f0) at snmp_api.c:5840
#7 snmp_free_pdu (pdu=0xffffa80133f0) at snmp_api.c:5809
#8 0x0000ffffada36a40 in snmp_sess_timeout
(sessp=sessp@entry=0xffffa8006710) at snmp_api.c:7189
#9 0x0000ffffada36b98 in snmp_timeout () at snmp_api.c:7017
#10 0x0000ffffada13a80 in snmp_synch_response_cb (ss=0xffffa8001660,
pdu=pdu@entry=0xffffa80133f0,
response=response@entry=0xffffacc96078, pcb=pcb@entry=0xffffada12f80
<snmp_synch_input>) at snmp_client.c:1085
#11 0x0000ffffada13bc4 in snmp_synch_response (ss=,
pdu=pdu@entry=0xffffa80133f0,
response=response@entry=0xffffacc96078) at snmp_client.c:1126

I have tried patches below patches as mentioned in
https://sourceforge.net/p/net-snmp/patches/1391/?limit=25, but issue
is still seen.

0002-snmplib-snmp_api-Remove-the-request-on-the-session-w.patch
0001-BUG2914-Agent-master-needs-to-treat-resend-as-normal.patch

Do I need to add any more patches to get this issue fixed.