(gdb) bt
#0  _int_malloc (av=0x7f1000000020, bytes=<value optimized out>) at malloc.c:4478
#1  0x00007f1045f37c70 in *__GI___libc_malloc (bytes=297) at malloc.c:3661
#2  0x00000000005622bf in _ast_malloc (len=297, file=0x5b3ab4 "manager.c", lineno=5060, func=0x5b7fa4 "append_event")
    at /usr/src/asterisk-1.8.14.1/include/asterisk/utils.h:457
#3  0x00000000004f749b in append_event (
    str=0xd2c0e88 "Event: VarSet\r\nPrivilege: dialplan,all\r\nChannel: SIP/5555-00001875\r\nVariable: RTPAUDIOQOS\r\nValue: ssrc=1542092895;themssrc=469756598;lp=0;rxjitter=0.000323;rxcount=8372;txjitter=0.000000;txcount=7817;"..., category=2048)
    at manager.c:5060
#4  0x00000000004f7a5b in __ast_manager_event_multichan (category=2048, event=0x5be668 "VarSet", chancount=0, chans=0x0,
    file=0x5b8b94 "pbx.c", line=10006, func=0x5bedc0 "pbx_builtin_setvar_helper",
    fmt=0x5be670 "Channel: %s\r\nVariable: %s\r\nValue: %s\r\nUniqueid: %s\r\n") at manager.c:5161
#5  0x000000000051e1c4 in pbx_builtin_setvar_helper (chan=0xd56ed98, name=0x5c1bc3 "RTPAUDIOQOS",
    value=0x7f1006860440 "ssrc=1542092895;themssrc=469756598;lp=0;rxjitter=0.000323;rxcount=8372;txjitter=0.000000;txcount=7817;rlp=0;rtt=0.000000") at pbx.c:10000
#6  0x000000000052726b in ast_rtp_instance_set_stats_vars (chan=0xd56ed98, instance=0xd8fab88) at rtp_engine.c:1619
#7  0x00007f1026a72d02 in sip_hangup (ast=0xd56ed98) at chan_sip.c:6390
#8  0x000000000046e298 in ast_hangup (chan=0xd56ed98) at channel.c:2837
#9  0x000000000050ee0f in __ast_pbx_run (c=0xd56ed98, args=0x0) at pbx.c:5237
#10 0x000000000050f137 in pbx_thread (data=0xd56ed98) at pbx.c:5329
#11 0x0000000000564cfe in dummy_start (data=0xd4bee60) at utils.c:1004
#12 0x00007f1045aa78ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#13 0x00007f1045f90b6d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#14 0x0000000000000000 in ?? ()