[asterisk-dev] [Code Review] 3603: func_jitterbuffer: fix errors and leaks caused by certain masquerade's

[Jonathan Rose]

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This review will probably need to account for this change in behavior when migrating to trunk:

https://reviewboard.asterisk.org/r/3721/

- Jonathan Rose


On June 13, 2014, 1:48 p.m., Corey Farrell wrote:
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> (Updated June 13, 2014, 1:48 p.m.)
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> 
> Review request for Asterisk Developers, Joshua Colp and Matt Jordan.
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> Bugs: ASTERISK-22409
>     https://issues.asterisk.org/jira/browse/ASTERISK-22409
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> Repository: Asterisk
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> Description
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> During masquerade it is possible for the AST_JITTERBUFFER_FD to be cleared (set to -1).  This change adds a check when copying channel fd's to prevent clearing an FD with -1.  This seems to resolve the bad audio quality experienced after the masquerade.  When AST_JITTERBUFFER_FD was set to -1, this prevented the channel from polling that timer.  This caused RTP packets to be received late, and discarded.
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> The changes to func_jitterbuffer.c were created first.  ast_free(jbframe); is needed to prevent jbframe from leaking if it is rejected by jb_impl.  This ensures we don't start leaking packets if they are received too late or rejected by jb_impl for any other reason.
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> The second change to func_jitterbuffer prevents a leak of ast_null_frame's that were duplicated (ie with ast_frdup or ast_frisolate).  I believe this leak might actually be unrelated to the masquerade issue, and likely occurs for every single ast_null_frame.
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> Diffs
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>   /branches/11/main/channel.c 416102 
>   /branches/11/funcs/func_jitterbuffer.c 416102 
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> Diff: https://reviewboard.asterisk.org/r/3603/diff/
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> Testing
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> Verified the scenario outlined in ASTERISK-22409 no longer experiences audio quality loss, and no longer causes leaks (tested under valgrind).  I patched asterisk to ensure that ast_frfree performed an immediate free to ensure valgrind would report any attempted use after free.
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> In early testing, I used debug messages instead of the added ast_frfree's - I verified the leaked frames reported by valgrind matched exactly to the number of debug messages.
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> For the masquerade fix I tested with some debug code that showed the old and new FD, this is how I found the valid FD being replaced by -1.  See JIRA ticket for example output.
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> I have not tested this issue or fix against 12+, but the relevant code is the same as 11 - func_jitterbuffer code was moved to core but still the same code.
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> Thanks,
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> Corey Farrell
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