[asterisk-bugs] [Asterisk 0016517]: Segfault while setting up T.38 fax reception

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16517 
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Reported By:                bklang
Assigned To:                dvossel
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Project:                    Asterisk
Issue ID:                   16517
Category:                   Channels/chan_sip/T.38
Reproducibility:            always
Severity:                   crash
Priority:                   normal
Status:                     closed
Asterisk Version:           SVN 
JIRA:                       SWP-700 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): 1.6.1 
SVN Revision (number only!): 236360 
Request Review:              
Resolution:                 fixed
Fixed in Version:           
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Date Submitted:             2009-12-26 16:00 CST
Last Modified:              2010-02-02 16:33 CST
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Summary:                    Segfault while setting up T.38 fax reception
Description: 
I have been experimenting with T.38 fax reception via SIP.  This results in
an immediate crash.  While I am able to capture a coredump, for whatever
reason GDB and MDB do not appear to be able to give me a usable backtrace. 
However, Asterisk logs these message immediately before crashing:

[Dec 26 21:06:25]     -- Executing [fax at standard-fax:2]
ReceiveFAX("SIP/broadriver-00000000",
"/var/spool/fax/1261861580.0.fax,debug") in new stack
[Dec 26 21:06:25] NOTICE[23097]: channel.c:2933 __ast_read: Dropping
incompatible voice frame on SIP/broadriver-00000000 of format slin since
our native format has changed to 0x4 (ulaw)
grant*CLI> [Dec 26 21:06:25] WARNING[23097]: udptl.c:766
calculate_far_max_ifp: (no tag): Cannot calculate far_max_ifp before
far_max_datagram has been set.
[Dec 26 21:06:25] WARNING[23097]: udptl.c:766 calculate_far_max_ifp: (no
tag): Cannot calculate far_max_ifp before far_max_datagram has been set.

Next I tried forcing the max datagram in sip.conf like this:

[general]
t38pt_udptl=yes,maxdatagram=400

However, Asterisk still crashes with the same message.

Out of curiosity, I modified main/udptl.c at line 764 in the function
calculate_far_max_ifp() to force the far_max_datagram to 400:

udptl->far_max_datagram = 400;

Doing this prevents Asterisk from segfaulting.

I wish I could share a backtrace, but so far I can't produce anything
useful.  I am willing to post the entire core dump if that would be
helpful.

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Relationships       ID      Summary
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duplicate of        0016724 coredump on T.38 Session with 1.6.2.1
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---------------------------------------------------------------------- 
 (0117586) svnbot (reporter) - 2010-02-02 16:33
 https://issues.asterisk.org/view.php?id=16517#c117586 
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Repository: asterisk
Revision: 244447

_U  branches/1.6.0/
U   branches/1.6.0/channels/chan_sip.c
U   branches/1.6.0/include/asterisk/udptl.h
U   branches/1.6.0/main/udptl.c

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r244447 | dvossel | 2010-02-02 16:32:56 -0600 (Tue, 02 Feb 2010) | 23
lines

Merged revisions 244443 via svnmerge from 
https://origsvn.digium.com/svn/asterisk/trunk

........
  r244443 | dvossel | 2010-02-02 16:27:23 -0600 (Tue, 02 Feb 2010) | 18
lines
  
  fixes crash during T.38 negotiation caused by invalid or missing
FaxMaxDatagram field
  
  AST-2010-001
  
  (closes issue https://issues.asterisk.org/view.php?id=16634)
  Reported by: krn
  
  (closes issue https://issues.asterisk.org/view.php?id=16724)
  Reported by: barthpbx
  
  (closes issue https://issues.asterisk.org/view.php?id=16517)
  Reported by: bklang
  
  (closes issue https://issues.asterisk.org/view.php?id=16485)
  Reported by: elsto
........

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http://svn.digium.com/view/asterisk?view=rev&revision=244447 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-02-02 16:33 svnbot         Checkin                                      
2010-02-02 16:33 svnbot         Note Added: 0117586                          
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