[tor-bugs] #18686 [Tor]: tor port forwarding claims to kill long-dead forwarder

[Tor Bug Tracker & Wiki]

#18686: tor port forwarding claims to kill long-dead forwarder
----------------------------+--------------------------
     Reporter:  chadmiller  |      Owner:
         Type:  defect      |     Status:  new
     Priority:  Medium      |  Milestone:
    Component:  Tor         |    Version:  Tor: 0.2.7.6
     Severity:  Major       |   Keywords:
Actual Points:              |  Parent ID:
       Points:              |   Reviewer:
      Sponsor:              |
----------------------------+--------------------------
 Mar 30 09:36:07 h Tor[1243]: tor_check_port_forwarding(): Started port
 forwarding helper (.../bin/tor-fw-helper) with pid '5936'
 Mar 30 09:36:09 h Tor[1243]: notify_waitpid_callback_by_pid(): Child
 process 5936 has exited; running callback.
 Mar 30 09:41:13 h Tor[1243]: Failed to terminate process with PID '5936'
 ('Success').

 Mar 30 09:41:13 h Tor[1243]: tor_check_port_forwarding(): Started port
 forwarding helper (...bin/tor-fw-helper) with pid '5985'
 Mar 30 09:41:15 h Tor[1243]: notify_waitpid_callback_by_pid(): Child
 process 5985 has exited; running callback.
 Mar 30 09:46:19 h Tor[1243]: Failed to terminate process with PID '5985'
 ('Success').

 Mar 30 09:46:19 h Tor[1243]: tor_check_port_forwarding(): Started port
 forwarding helper (.../bin/tor-fw-helper) with pid '6052'
 Mar 30 09:46:21 h Tor[1243]: notify_waitpid_callback_by_pid(): Child
 process 6052 has exited; running callback.
 Mar 30 09:51:25 h Tor[1243]: Failed to terminate process with PID '6052'
 ('Success').

 Mar 30 09:51:25 h Tor[1243]: tor_check_port_forwarding(): Started port
 forwarding helper (.../bin/tor-fw-helper) with pid '8784'
 Mar 30 09:51:27 h Tor[1243]: notify_waitpid_callback_by_pid(): Child
 process 8784 has exited; running callback.
 Mar 30 09:56:31 h Tor[1243]: Failed to terminate process with PID '8784'
 ('Success').

 Mar 30 09:56:31 h Tor[1243]: tor_check_port_forwarding(): Started port
 forwarding helper (.../bin/tor-fw-helper) with pid '8848'
 Mar 30 09:56:33 h Tor[1243]: notify_waitpid_callback_by_pid(): Child
 process 8848 has exited; running callback.
 Mar 30 10:01:37 h Tor[1243]: Failed to terminate process with PID '8848'
 ('Bad file descriptor').


 tor_check_port_forwarding in util.c keeps a static process_handle_t .
 Before spawning the forwarder helper, it says it tries to kill previously-
 running instances.

 The cause is that the killing function doesn't distinguish between between
 not needing to kill versus attempted and failed.

 The resulting error message has a ugly, wrong error reason too.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18686>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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