[asterisk-bugs] [JIRA] (ASTERISK-25645) res_rtp_asterisk: Lock inversion

[Steve Davies (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-25645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=228738#comment-228738 ] 

Steve Davies edited comment on ASTERISK-25645 at 12/24/15 5:46 AM:
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Is the attached patch 'experimental_anti_deadlock' utterly stupid?

It tries to make sure that dtls->lock is always held when calling dtls_srtp_check_pending() and then if a call to __rtp_sendto() is necessary, it releases the lock and re-acquires it to prevent a potential deadlock.

It cures my issue, but is the locking and unlocking a bit overkill?


was (Author: one47):
It the attached patch 'experimental_anti_deadlock' utterly stupid?

It tries to make sure that dtls->lock is always held when calling dtls_srtp_check_pending() and then if a call to __rtp_sendto() is necessary, it releases the lock and re-acquires it to prevent a potential deadlock.

It cures my issue, but is the locking and unlocking a bit overkill?

> res_rtp_asterisk: Lock inversion
> --------------------------------
>
>                 Key: ASTERISK-25645
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-25645
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_rtp_asterisk
>            Reporter: Joshua Colp
>         Attachments: deadlocked_threads.txt, experimental_anti_deadlock
>
>
> Reported by Steve Davies on asterisk-dev:
> commit 5e6b1476a087407a052f007d326c504cfeefebe7
> ASTERISK-25614
> 2 code paths which approximate the following will cause a lock-inversion deadlock:
> approximate call orders are:
> a)
> pj_timer_heap_poll (PJ_LOCK)
> ast_rtp_on_ice_complete
> ast_rtp_instance_set_remote_address
> remote_address_set
> ast_rtp_remote_address_set
> (DTLS_LOCK)
> ...
> b)
> ast_pbx...
> app_dial
> bridge...
> read
> rtp_read
> ...
> __rtp_recvfrom
> (DTLS_LOCK)
> dtls_srtp_check_pending
> __rtp_sendto
> pj_ice_sess_send_data
> (PJ_LOCK)



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