[asterisk-bugs] [JIRA] (ASTERISK-27617) Frack (crash), excessive refcount during Jitterbuffer operation

[Colin (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-27617?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=241820#comment-241820 ] 

Colin commented on ASTERISK-27617:
----------------------------------

Thank you. We will do the upgrade to 15.2 or later. Perhaps you could explain the connection between the fixed issues and ours, which seems specifically to be caused by an incremented reference count on the field referring to media format of a frame used by the jitterbuffer. Perhaps one of those issues has produced a situation where there is an excessive reference count and the jitterbuffer media field read was "the straw that broke the camel's back" - only time will tell. I'd like to understand the causal connection, but I think that requires a better knowledge of frame memory management than I currently have.

> Frack (crash), excessive refcount during Jitterbuffer operation
> ---------------------------------------------------------------
>
>                 Key: ASTERISK-27617
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27617
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Core/Jitterbuffer
>    Affects Versions: 14.6.0
>         Environment: Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-109-generic x86_64) 
>  
>            Reporter: Colin
>            Assignee: Colin
>              Labels: pjsip
>         Attachments: CoreDump-brief.txt, CoreDump-full.txt, CoreDump-thread1.txt, jitterbuffer frack.txt
>
>
> During an __ast_read operation on a pushed frame (in abstract_jb::hook_event_cb()), the reference count on the ast_frame_subclass resulted in a FRACK, and system crash. 
> The referenced field which triggered the failed assert was out->subclass.format - a reference to the Asterisk media format. Bumping this causes the EXCESSIVE_REF_COUNT to be exceeded.
> This instance of Asterisk was participating in a Stasis application, with around 28 callers. At the time of the crash around 20 were muted, but no bridge or channel operations were being carried out by the Stasis application.
> Core dump included as text file.



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