[asterisk-dev] [Code Review] 3908: ARI: Fix bug where hanging up while in a bridge during playback causes a crash

[Jonathan Rose]

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https://reviewboard.asterisk.org/r/3908/
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(Updated Aug. 20, 2014, 4:21 p.m.)


Review request for Asterisk Developers, kmoore, Matt Jordan, and rmudgett.


Changes
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More stringent checking for if the channel is still in a bridge plus command destructors added to the command queue


Bugs: ASTERISK-24147
    https://issues.asterisk.org/jira/browse/ASTERISK-24147


Repository: Asterisk


Description
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Here's a basic rundown of what was happening:

1. Stasis application with a channel in it, channel is in a bridge.  Playback actions for the channel are queued, the stasis control is running them.

2. The channel hangs up. Because the stasis control detects a hangup and the depart is expected to be handled when the channel leaves the bridge, the stasis application execution function exits taking the control along with it. When the PBX thread exits, the channel is considered fully hung up and leaves the bridging core. At this point we are running after bridge callbacks with, one of which holds a pointer to a dead control object that we are trying to do all queue actions to along with other things.  This causes the crash.

In order to fix this, I made sure that if the control execution loop is exited without pulling the channel out of the bridge that the channel depart would occur manually and the control would be marked so that the after bridge cb wouldn't attempt to exit the bridge in this case. This wasn't actually causing problems, but Richard and I both have concerns about an after bridge callback attempting to depart a channel from a bridge... it seems a little out there.


Diffs (updated)
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  /branches/12/res/stasis/stasis_bridge.c 421424 
  /branches/12/res/stasis/control.c 421424 
  /branches/12/res/stasis/command.c 421424 
  /branches/12/res/stasis/command.h 421424 
  /branches/12/res/res_stasis_recording.c 421424 
  /branches/12/res/res_stasis_playback.c 421424 
  /branches/12/res/res_stasis_answer.c 421424 
  /branches/12/res/res_stasis.c 421424 
  /branches/12/include/asterisk/stasis_app_impl.h 421424 

Diff: https://reviewboard.asterisk.org/r/3908/diff/


Testing
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Made sure the crash that was happening no longer occurs

Tested long queues of playback to check what would happen with the additional playbacks.  Each subsequent playback from the one currently running fails (in an expected manner) and reports its failure over stasis.  Nothing too odd there.


Thanks,

Jonathan Rose

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