[asterisk-bugs] [JIRA] (ASTERISK-26867) autochan: Locking in a function ast_autochan_destroy() on destroyed channel (after masquerade).

[Friendly Automation (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-26867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=236041#comment-236041 ] 

Friendly Automation commented on ASTERISK-26867:
------------------------------------------------

Change 5221 merged by zuul:
autochan/mixmonitor/chanspy: Fix unsafe channel locking and references.

[https://gerrit.asterisk.org/5221|https://gerrit.asterisk.org/5221]

> autochan: Locking in a function ast_autochan_destroy() on destroyed channel (after masquerade).
> -----------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-26867
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26867
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Applications/app_mixmonitor
>    Affects Versions: 11.25.1, 13.14.0
>         Environment: Ubuntu 12.04
>            Reporter: Krzysztof Trempala
>            Assignee: Richard Mudgett
>
> We have a problem with ramdom locking in a function ast_autochan_destroy() on destroyed channel (after masquerade).
>  
> This situation is when recording channel (mixmonitor) and stop recording on masquerade event. Then in separate threads are executed functions:
>  - ast_autochan_destroy() in mixmonitor_thread() and
>  - ast_autochan_new_channel() in ast_do_masquerade().
> Used variable (not thread safe) "autochan".
> {code} 
>   +------------------------------------------------------+
>   | MIXMONITOR THREAD                                    |
>   +------------------------------------------------------+
>   mixmonitor_thread()
>   ...
>   ast_autochan_destroy()
>   ...
>   ast_autochan_channel_lock(autochan);
>   #define ast_autochan_channel_lock(autochan) \
>     do { \                                                    +----------------------------------------------------+
>       struct ast_channel *autochan_chan = autochan->chan; \   | CHANNEL THREAD                                     |
>             <-------------------------------------------------+                                                    |
>       ast_channel_lock(autochan_chan); \                      | channel_do_masquerade()                            |
>       if (autochan->chan == autochan_chan) { \                | ...                                                |
>         break; \                                              | void ast_autochan_new_channel(old_chan, new_chan)  |
>       } \                                                     | {                                                  |
>       ast_channel_unlock(autochan_chan); \                    |   ...                                              |
>       } while (1)                                             |   autochan->chan = ast_channel_unref(old_chan);    |
>                                                               |   autochan->chan = ast_channel_ref(new_chan);      |
>                                                               |   ...                                              |
>                                                               | }                                                  |
>                                                               | ...                                                |
>                                                               | destroy(old_chan);                                 |
>                                                               | ...                                                |
>                                                               +----------------------------------------------------+
> {code} 



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