[asterisk-bugs] [Asterisk 0017390]: [patch] Race conditition in app_meetme leads to crash

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=17390 
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Reported By:                Vince
Assigned To:                jpeeler
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Project:                    Asterisk
Issue ID:                   17390
Category:                   Applications/app_meetme
Reproducibility:            random
Severity:                   crash
Priority:                   normal
Status:                     ready for review
Target Version:             1.4.35
Asterisk Version:           1.4.31 
JIRA:                       SWP-1528 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-05-24 17:42 CDT
Last Modified:              2010-07-12 15:34 CDT
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Summary:                    [patch] Race conditition in app_meetme leads to
crash
Description: 
I have been tracking down random crashes on a number of Asterisk servers
that rely heavily on app_meetme conference rooms. Depending on the server
load they can crash upto several times a week.

The majority of core dumps seem to be related to insufficient locking on
the conference 'userlist' linked list structure.

I have attached to patch to fix the locations where I think thread locks
are missing. Applies against 1.4.31. I have quickly glanced at the 1.6.x
branch and this looks to be required there too but I have no servers to
test that version on.
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 (0124524) svnbot (reporter) - 2010-07-12 15:34
 https://issues.asterisk.org/view.php?id=17390#c124524 
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Repository: asterisk
Revision: 275773

U   branches/1.4/apps/app_meetme.c

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r275773 | jpeeler | 2010-07-12 15:34:50 -0500 (Mon, 12 Jul 2010) | 12
lines

Make user removals and traversals thread safe in meetme.

Race conditions present in meetme involving the user list where a lack of
locking has the potential for a user to be removed during a traversal or
as in
the case of the reporter after checking if the list is empty could cause a
crash. Fixing this was done by convering the userlist to an ao2 container.

(closes issue https://issues.asterisk.org/view.php?id=17390)
Reported by: Vince

Review: https://reviewboard.asterisk.org/r/746/

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http://svn.digium.com/view/asterisk?view=rev&revision=275773 

Issue History 
Date Modified    Username       Field                    Change               
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2010-07-12 15:34 svnbot         Checkin                                      
2010-07-12 15:34 svnbot         Note Added: 0124524                          
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