[asterisk-bugs] [JIRA] (ASTERISK-24234) app_meetme: Crash on conference shutdown due to NULL channel passed to meetme_stasis_generate_msg()

[Shaun Ruffell (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-24234?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shaun Ruffell updated ASTERISK-24234:
-------------------------------------

    Attachment: 0001-channels-Do-not-crash-if-NULL-channel-passed-to-ast_.patch

I got things working at home with patch [^0001-channels-Do-not-crash-if-NULL-channel-passed-to-ast_.patch] but it doesn't seem right. I pinged #asterisk-dev and mjordan had this conversation with me:

{noformat}
sruffell
My basic question is what should meetme_stasis_generate_msg() emit when the channel is NULL.
mjordan
11:03
looks
11:04
hm
11:04
that function is documented as being NULL tolerant, but clearly is not
11:04
I think when we went through and did the performance improvements, we messed that up.
sruffell
11:05
it looks like the null tollerance was removed in commit 404260
11:05
arghh..wait..wrong revision
11:05
404260: https://github.com/sruffell/asterisk-working/commit/8d70015cdd4
mjordan
11:06
Hm.
11:06
well, that would crash as well
11:06
ast_channel_blob_create is null tolerant
11:06
ast_channel_blob_create_from_cache is not, however
11:07
neither is grabbing ast_channel_uniqueid
11:07
it should just use  ast_channel_blob_create. You have to use that one if you allow for NULL channels.
mjordan
11:07
sruffell: mind making an issue?
sruffell
11:07
nope..not at all…will do.  
mjordan
11:08
sruffell: ast_channel_blob_create creates a 'snapshot' of a channel, which is a relatively expensive thing to do. If what you want is a snapshot but you know the state of the channel hasn't changed, you can get it from the cache
mjordan
11:09
in this case, we know that the state of the channel hasn't changed; the state of MeetMe has. However, this method gets called with and without a channel... and ast_channel_blob_create does more than just pack a channel into something that can be delivered over Stasis
11:09
ast_channel_topic is also NULL safe
sruffell
11:10
hmm..ok.
mjordan
11:10
sruffell: the locking if the channel is present is probably still necessary, so kharwell's patch should be restored, but should check for chan being NULL before locking/unlocking.
mjordan
11:10
(If you felt like writing a patch :-) )
sruffell
11:11
:) I will. I had written this one: https://github.com/sruffell/asterisk-working/commit/bf6bddcc7963f3aacc223108b36dc6501    in order to get things working, just didn't seem like the right thing. But it's what I running at home right now (beta-1 + that patch)
mjordan
11:15
sruffell: heh. That would do interesting things :-)
{noformat}

So I'll see about updating the patch to use and testing it out tonight.

> app_meetme: Crash on conference shutdown due to NULL channel passed to meetme_stasis_generate_msg()
> ---------------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-24234
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-24234
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Applications/app_meetme
>    Affects Versions: 13.0.0-beta1
>            Reporter: Shaun Ruffell
>         Attachments: 0001-channels-Do-not-crash-if-NULL-channel-passed-to-ast_.patch
>
>
> Updated from an old version of 12 to 13-beta1 last night. Called into a meetme conference and when I left the conference asterisk crashed.
> The backtrace:
> {noformat}
> #0 in ast_channel_uniqueid (chan=0x0) at channel_internal_api.c:489
>   #1 in meetme_stasis_generate_msg (meetme_conference=0xb724b5e8, chan=0x0, user=0x0, message_type=0x85a6afc, extras=0x0) at app_meetme.c:1383
>   #2 in conf_free (conf=0xb724b5e8) at app_meetme.c:2326
>   #3 in dispose_conf (conf=0xb724b5e8) at app_meetme.c:2503
>   #4 in conf_exec (chan=0xb7ef50ec, data=0xb738cbe8 "1337,i") at app_meetme.c:5138
>   #5 in pbx_exec (c=0xb7ef50ec, app=0x85a7d38, data=0xb738cbe8 "1337,i") at pbx.c:1658
>   #6 in pbx_extension_helper (c=0xb7ef50ec, con=0x0, context=0xb7ef5774 "phones", exten=0xb7ef57c4 "1337", priority=5, label=0x0, callerid=0xb7e759c8 "6001", action=E_SPAWN, found=0xb738f060, combined_find_spawn=1) at pbx.c:4930
>   #7 in ast_spawn_extension (c=0xb7ef50ec, context=0xb7ef5774 "phones", exten=0xb7ef57c4 "1337", priority=5, callerid=0xb7e759c8 "6001", found=0xb738f060, combined_find_spawn=1) at pbx.c:5945
> {noformat}



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