IT31676: BIPMQTT CAN CRASH WITH A SEGFAULT DURING HEAVY TRAFFIC SCENARIOS

APAR status

• Closed as program error.

Error description

• The bipMQTT process can crash with a segmentation fault when
  experiencing heavy traffic. Very few diagnostics will be
  generated, for example no abend file will be created and a core
  dump will not necessarily be generated. If a core dump is
  generated the following stack may be seen:
  
  
  
  #0
  0x0000000000412496 in _mosquitto_read_uint16 (packet=0x24da5a8,
  word=0x7fff929dad7a) at
  /usr/local/src/mosquitto/lib/net_mosq.c:637
  
  #1
  0x000000000041230f in _mosquitto_read_string (packet=0x24da5a8,
  str=0x7fff929dadd0) at
  /usr/local/src/mosquitto/lib/net_mosq.c:606
  
  #2
  0x000000000041314c in mqtt3_handle_publish (db=0x625ca0,
  context=0x24da560) at
  /usr/local/src/mosquitto/src/read_handle.c:104
  
  #3
  0x000000000041301e in mqtt3_packet_handle (db=0x625ca0,
  context=0x24da560) at
  /usr/local/src/mosquitto/src/read_handle.c:48
  
  #4
  0x0000000000412e55 in _mosquitto_packet_read (db=0x625ca0,
  mosq=0x24da560) at
  /usr/local/src/mosquitto/lib/net_mosq.c:1021
  
  #5
  0x000000000040f109 in loop_handle_reads_writes (db=0x625ca0,
  pollfds=0x24da2f0) at
  /usr/local/src/mosquitto/src/loop.c:472
  
  #6 0x000000000040e94a
  in mosquitto_main_loop (db=0x625ca0, listensock=0x24d8550,
  listensock_count=2, listener_max=4) at
  /usr/local/src/mosquitto/src/loop.c:292
  
  #7 0x000000000040fd4c
  in main (argc=1, argv=0x7fff929db838) at
  /usr/local/src/mosquitto/src/mosquitto.c:366
  
  
  
  Though it is
  not guaranteed that the back trace will be readable.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All users of IBM Integration Bus v10 and App Connect Enterprise
  v11 who use bipMQTT as an MQTT broker for production data.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  The bipMQTT process can crash with a segmentation fault when
  experiencing heavy traffic. Very few diagnostics will be
  generated, for example no abend file will be created and a core
  dump will not necessarily be generated. If a core dump is
  generated the following stack may be seen:
  
  #0 0x0000000000412496 in _mosquitto_read_uint16
  (packet=0x24da5a8, word=0x7fff929dad7a) at
  /usr/local/src/mosquitto/lib/net_mosq.c:637
  #1 0x000000000041230f in _mosquitto_read_string
  (packet=0x24da5a8, str=0x7fff929dadd0) at
  /usr/local/src/mosquitto/lib/net_mosq.c:606
  #2 0x000000000041314c in mqtt3_handle_publish (db=0x625ca0,
  context=0x24da560) at
  /usr/local/src/mosquitto/src/read_handle.c:104
  #3 0x000000000041301e in mqtt3_packet_handle (db=0x625ca0,
  context=0x24da560) at
  /usr/local/src/mosquitto/src/read_handle.c:48
  #4 0x0000000000412e55 in _mosquitto_packet_read (db=0x625ca0,
  mosq=0x24da560) at /usr/local/src/mosquitto/lib/net_mosq.c:1021
  #5 0x000000000040f109 in loop_handle_reads_writes (db=0x625ca0,
  pollfds=0x24da2f0) at /usr/local/src/mosquitto/src/loop.c:472
  #6 0x000000000040e94a in mosquitto_main_loop (db=0x625ca0,
  listensock=0x24d8550, listensock_count=2, listener_max=4) at
  /usr/local/src/mosquitto/src/loop.c:292
  #7 0x000000000040fd4c in main (argc=1, argv=0x7fff929db838) at
  /usr/local/src/mosquitto/src/mosquitto.c:366
  
  Though it is not guaranteed that the back trace will be
  readable.
  
  This is Mosquitto bug 463241 -
  https://bugs.eclipse.org/bugs/show_bug.cgi?id=463241
  

Problem conclusion

• The product has been updated to use mosquitto 1.6.8 for bipMQTT
  which is not susceptible to this issue. Additionally the
  stdout/stderr for the bipMQTT process will now be written to the
  decidated file <WORKPATH>/components/<BROKER>/bipMQTT.txt on
  v10. Previously this output would be discarded on Windows and
  written to the stdout/stderr file for the bipbroker process on
  other platforms. The stdout/stderr for bipMQTT continues to be
  written to <WORKPATH>/components/<BROKER>/bipMQTT.stdout and
  <WORKPATH>/components/<BROKER>/bipMQTT.stderr respectively.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v10.0      10.0.0.21
  v11.0      11.0.0.9
  
  The latest available maintenance can be obtained from:
  http://www-01.ibm.com/support/docview.wss?rs=849&uid=swg27006041
  
  If the maintenance level is not yet available,information on
  its planned availability can be found on:
  http://www-1.ibm.com/support/docview.wss?rs=849&uid=swg27006308
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  INTEGRATION BUS

• Fixed component ID

  5724J0540

Applicable component levels