[asterisk-bugs] [Asterisk 0016271]: [patch] message limit (maxmsg) can be exceeded in 1.6.x creating orphan voicemail

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16271 
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Reported By:                sohosys
Assigned To:                tilghman
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Project:                    Asterisk
Issue ID:                   16271
Category:                   Applications/app_voicemail
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     ready for testing
Target Version:             1.6.0.22
Asterisk Version:           SVN 
JIRA:                       SWP-432 
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:             2009-11-18 08:27 CST
Last Modified:              2010-01-08 09:32 CST
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Summary:                    [patch] message limit (maxmsg) can be exceeded in
1.6.x creating orphan voicemail
Description: 
If two are more users are in the process of leaving a voicemail message,
and the count of messages in the mailbox was maxmsg-1 when they started
leaving the message, the application will record all new messages.

Messages will be numbered in the order they were completed, and all
messages over the limit will be inaccessible to the end user. We have
tested up to 5 callers in voicemail resulting in maxmsg+4 messages and 4
inaccessible messages. I assume there is no limit based on the code.

We run some high volume asterisk servers where this has become common. In
the 1.6 series the message is not reported and not accessible by the end
user, although the caller that left the last messages(s) had no indication
of the full mailbox.

I guess this could be classified as minor or major depending on the
content of the messages in the black hole and the job title of the mailbox
owner.

In the 1.2.x series a crash is the result when the end user tries to
access the last messages in the mailbox, and we fixed that by simply adding
10 to our desired maxmsg count in voicemail.conf and changing the code to
test for msgcount <= maxmsg - 10 before accepting a new message, but the
1.6 code is more complex, and our 1.2 solution is too primitive for a
current version, although transparently buffering the variables might be a
good simple solution.
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Relationships       ID      Summary
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related to          0015117 crash in voicemail when more than maxms...
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 (0116301) sohosys (reporter) - 2010-01-08 09:32
 https://issues.asterisk.org/view.php?id=16271#c116301 
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i do not believe the most recent patch eliminates the bug, but rather makes
it more unlikely that it will surface. In a very heavily loaded system with
a shared voicemail box it is still very possible to duplicate the bug by
exceeding the maxmsg count by 11 messages.

why not derive the loop counter from the actual count of message files in
the file structure rather than using a fudge factor of 10? 

Issue History 
Date Modified    Username       Field                    Change               
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2010-01-08 09:32 sohosys        Note Added: 0116301                          
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