[asterisk-dev] [Code Review]: Fix a large variety of errors caused by negative return codes

Matt Jordan reviewboard at asterisk.org
Fri Apr 13 15:40:08 CDT 2012 


> On April 13, 2012, 2:42 p.m., rmudgett wrote:
> > /branches/1.8/main/manager.c, lines 3624-3645
> > <https://reviewboard.asterisk.org/r/1863/diff/3/?file=27253#file27253line3624>
> >
> >     You cannot use astman_send_error here since you have a partially created command response already.  You need to use astman_append instead to output your error message as part of the command response.

I'm not sure about that, although I agree that astman_send_error without first terminating the in flight event isn't correct either.

As I see it, we have three options:

1. When an error occurs during response construction, we immediately terminate the current response, and send an error message.  This would look like:

Response: Follows
Privilege: Command
ActionID: 1234
blah blah blah yackity I'm a CLI output
and now I've failed
--END COMMAND--


Response: Failure
ActionID: 1234
Message: Command response construction error

2. When an error occurs during response construction, we instead embed the failure as a sort of warning in the response.  This would look like:
Response: Follows
Privilege: Command
ActionID: 1234
blah blah blah yackity I'm a CLI output
and now I've failed
--END COMMAND--
Message: Command response construction error

3. Or, we attempt to buffer the whole CLI response in memory before sending it.  This would allows us to either send the whole thing successfully, or an error response.  I'm concerned about this approach only because the CLI output could be rather largish (memory allocations comes to mind), and trying to buffer it all in memory may be a bad idea.

My preference would be to do #1, since it doesn't mess around with any current response parsing, and both messages are in the format currently expected.  I'm not sure if anyone expects to get two Response events however.


> On April 13, 2012, 2:42 p.m., rmudgett wrote:
> > /branches/1.8/main/translate.c, line 1120
> > <https://reviewboard.asterisk.org/r/1863/diff/3/?file=27254#file27254line1120>
> >
> >     x can never be 0 here as well.

Yes, the AST_FORMAT_AUDIO_MASK precludes that.  Changed to comment.


> On April 13, 2012, 2:42 p.m., rmudgett wrote:
> > /branches/1.8/main/translate.c, line 1155
> > <https://reviewboard.asterisk.org/r/1863/diff/3/?file=27254#file27254line1155>
> >
> >     same here

Yes, the AST_FORMAT_VIDEO_MASK precludes that.  Changed to comment.


- Matt


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On April 13, 2012, 1:49 p.m., Matt Jordan wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/1863/
> -----------------------------------------------------------
> 
> (Updated April 13, 2012, 1:49 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> Through a static analysis tool, a large number of errors were found that dealt with using potential negative return values in harmful ways.  The following is a summary of the changes for the various affected files:
> 
> * app_voicemail
>   - a negative result from lseek is later passed into mmap as the size of the memory map
>   - a negative result from read closes the various file descriptors and unlinks the output file, but the next check against the return value only checks to see if its non-zero
> * chan_agent - ast_channel_unlock returns a negative value if the item passed to it is NULL or an invalid ao2 object.  strerror cannot accept a negative value.
> * chan_dahdi - if dahdi_get_index returns a negative value, we index directly into an array
> * format_* - various errors not checking return values of ftello and fseek, and passing the results into functions that expect non-negative values
> * func_env - various places where the result of ftello was directly used as input to functions that expect non-negative values
> * asterisk
>   - the request to read returns a negative value.  This causes us to enter into the retry logic.  If we attempt to reconnect and succeed, we would normally proceed in the for(;;) loop and attempt to index into buf using the negative return value from read.  Instead, if we do reconnect, we immediately return to the beginning of the for(;;) loop and attempt a new read.
>   - similar situation - if a read fails, don't attempt to index into a buffer using the return value
> * frame - if we can't determine a preferred codec using the provided values, don't attempt to use an index value that never got set
> * manager 
>   - various failures of mkstemp, lseek were not checked for and could be provided to methods that don't handle negative numbers
>   - passing a negative result from lseek into mmap as the size of the memory map
> * translate - powerof can return a negative result if no bits are set, which would then be used as an index into an array
> * res_agi - if read returns an error, we treated it as if bytes were read from the pipe
> * res_musiconhold - if we fail to spawn spawn_mp3 returns a negative number, we wait a bit and attempt again later.  However, the return 'file descriptor' srcfd is later passed into read.
> * res_rtp_asterisk - ast_rtp_codecs_payload_code can return a negative value if no codecs are found that match between instance1 and the specified payload.  If that's the case, the bridge should be broken, as there are no compatible formats between the two different endpoints (and we shouldn't index into an array using the return value)
> 
> 
> Diffs
> -----
> 
>   /branches/1.8/apps/app_voicemail.c 362134 
>   /branches/1.8/channels/chan_agent.c 362134 
>   /branches/1.8/channels/chan_dahdi.c 362134 
>   /branches/1.8/formats/format_g719.c 362134 
>   /branches/1.8/formats/format_g723.c 362134 
>   /branches/1.8/formats/format_g729.c 362134 
>   /branches/1.8/formats/format_gsm.c 362134 
>   /branches/1.8/formats/format_h263.c 362134 
>   /branches/1.8/formats/format_h264.c 362134 
>   /branches/1.8/formats/format_ilbc.c 362134 
>   /branches/1.8/formats/format_pcm.c 362134 
>   /branches/1.8/formats/format_siren14.c 362134 
>   /branches/1.8/formats/format_siren7.c 362134 
>   /branches/1.8/formats/format_sln.c 362134 
>   /branches/1.8/formats/format_sln16.c 362134 
>   /branches/1.8/formats/format_vox.c 362134 
>   /branches/1.8/formats/format_wav.c 362134 
>   /branches/1.8/formats/format_wav_gsm.c 362134 
>   /branches/1.8/funcs/func_env.c 362134 
>   /branches/1.8/main/asterisk.c 362134 
>   /branches/1.8/main/frame.c 362134 
>   /branches/1.8/main/manager.c 362134 
>   /branches/1.8/main/translate.c 362134 
>   /branches/1.8/res/res_agi.c 362134 
>   /branches/1.8/res/res_musiconhold.c 362134 
>   /branches/1.8/res/res_rtp_asterisk.c 362134 
> 
> Diff: https://reviewboard.asterisk.org/r/1863/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Matt
> 
>

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