Possible error in rtems_message_queue_send.

[Joel Sherrill]

pr1414 filed against 4.8 and closed.

sp49 added to cvs head.

Fix available for legacy releases of 4.6 and 4.7. 
Long term support for legacy RTEMS versions
is available from OAR.  We backport fixes like this
that impact older branches.  Contact me for details
on getting legacy support if your project is frozen
on an old branch.

--joel

Joel Sherrill wrote:
> Wendell Pereira da Silva wrote:
>   
>> Hi Joel,
>>
>>  
>>
>> After a lot of time in test effort of an application (based on RTEMS 
>> 4.8.0), I’ve found a strange behavior in rtems_message_queue_send().
>>
>> The context is illustrated as follows:
>>
>>  
>>
>> lenStatus = rtems_message_queue_send(mqID, &Msg, sizeof(Msg));
>>
>> if (lenStatus != RTEMS_SUCCESSFUL)
>>
>> {
>>
>>     errorRecovery(…);
>>
>> }
>>
>>  
>>
>> This code works fines if mqID identifies a valid message queue object 
>> with enough space. But a bug in my application turned mqID a valid 
>> TASK id. So, it was expected that the errorRecovery() function should 
>> be called but, surprisingly, rtems_message_queue_send() returned 
>> RTEMS_SUCCESSFUL (!).
>>
>>  
>>
>> Digging into the RTEMS source from rtems_message_queue_send(), I 
>> figured out that only the index part the object id (the last 
>> significant 16-bit) is used to find the object’s entry in the 
>> information->local_table (objectget.c). So, what happened was simply a 
>> coincidence: an index of a Task Object fit to index a Queue Object.
>>
>>  
>>
>> What is the right way to fix this?
>>
>>     
>
> Which RTEMS version?  This code is heavily optimized and may have been
> broken at some point.  The index is extracted this way now which should
> be right:
>
>   index = id - information->minimum_id + 1;
>
> What's the CVS Id? 
>
>   
>>  
>>
>> Solutions:
>>
>> (1) To put more complexity in rtems_message_queue_send() – hgrrr!. 
>> That is, code for verifying if the ID is really a queue id;
>>
>> (2) Move such verification code to the application level.
>>
>>  
>>
>>     
> No.  It looks like 4.9 and newer have the above logic which should
> be OK.  4.8 and older have a different logic which would suffer
> from what you see.
>
> Looks like a minor patch to use the above code all the time.
>
> And an addition of a test case. :)  Can you create a small one
> for me?
>
> Thanks.
>   
>>  
>>
>> Att.
>>
>>  
>>
>> Wendell Pereira da Silva
>>
>> *COMP***SIS** Computadores e Sistemas Ind. e Com. Ltda.
>> Aerospace Systems | [12] 2139-3966 ext. 977 | www.compsis.com.br 
>> <http://www.compsis.com.br/>
>>
>>  
>>
>>     
>
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> rtems-users at rtems.org
> http://www.rtems.org/mailman/listinfo/rtems-users
>   


-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985