ディスク支援キューが破損していると、rsyslog がセグメンテーション違反でクラッシュする

Issue

• rsyslog が起動時にセグメンテーション違反を起こし、systemd が無限ループで再起動を繰り返します。

  # systemctl start rsyslog
  Job for rsyslog.service failed because a fatal signal was delivered to the control process. See "systemctl status rsyslog.service" and "journalctl -xe" for details.
  
  # journalctl | grep rsyslog
  Nov 11 13:15:08 server rsyslogd[928855]: action-0-builtin:omfwd queue[DA]: error dequeueing element - ignoring, but strange things may happen
  Nov 11 13:15:08 server rsyslogd[928855]: action-0-builtin:omfwd queue[DA]: qDeqDisk error happened at around offset 84191 
  Nov 11 13:15:08 server rsyslogd[928855]: action-0-builtin:omfwd queue[DA]: error dequeueing element - ignoring, but strange things may happen
  Nov 11 13:15:08 server rsyslogd[928855]: action-0-builtin:omfwd queue[DA]: qDeqDisk error happened at around offset 84344 
  Nov 11 13:15:08 server rsyslogd[928855]: action-0-builtin:omfwd queue[DA]: error dequeueing element - ignoring, but strange things may happen
  Nov 11 13:15:08 server kernel: traps: rs:action-0-bui[928866] general protection fault ip:55f977d51779 sp:7fb6251eb9b0 error:0 in rsyslogd[55f977d0c000+6b000]
  Nov 11 13:15:08 server systemd-coredump[928963]: Resource limits disable core dumping for process 928855 (rsyslogd).
  Nov 11 13:15:08 server systemd-coredump[928963]: Process 928855 (rsyslogd) of user 0 dumped core.
  Nov 11 13:15:08 server systemd[1]: rsyslog.service: Main process exited, code=dumped, status=11/SEGV
  Nov 11 13:15:08 server systemd[1]: rsyslog.service: Failed with result 'core-dump'.
  Nov 11 13:15:08 server systemd[1]: rsyslog.service: Scheduled restart job, restart counter is at 5.
  Nov 11 13:15:08 server systemd[1]: Stopped System Logging Service.
  Nov 11 13:15:08 server systemd[1]: rsyslog.service: Start request repeated too quickly.
  Nov 11 13:15:08 server systemd[1]: rsyslog.service: Failed with result 'core-dump'.
  Nov 11 13:15:08 server systemd[1]: Failed to start System Logging Service.
  

• rsyslog は、デバッグモードで次のメッセージを stderr に表示します。

  <Obj:1:msg:1:
  +iProtocolVersion:2:1:0:
  +iSeverity:2:1:5:
  +iFacility:2:2:16:
  +m'
  3817.443895127:action 0 queue[DA]:Reg/w0: error property name: 'iFacilit<Obj'
  3817.443898262:action 0 queue[DA]:Reg/w0: error var type: '1'
  Segmentation fault
  

• dmesg の出力には次のメッセージが表示されます。

  kernel: rs:action 0 que[29724]: segfault at 5 ip 0000558247132cec sp 00007f75b3cbfb50 error 4 in rsyslogd[55824710c000+95000]