Problem with rtems_task_variable_delete

Paul Whitfield paulw at
Tue Dec 9 02:46:58 UTC 2003

Dieter Schaefer wrote:

> Hello,
> trying to get telnetd to work (powerpc, rtems-4.6.0pre5) I experienced 
> the following problem ...
> trying various commands everything seems to work Ok, until I try to 
> logoff from the telnet session. The system crashes, mean end up 
> in the BSP panic handler.
> Digging into the problem, it seems to be related with deleting a task variable.
> If the task variable contains a pointer to malloc'ed memory and 'free' is 
> passed to rtems_task_variable_add it will crash on deleting the task. 
> Background: telnetd uses shell, and shell creates a 'user environment' 
> after issuing a 'logoff', shell tries to execute a 
> rtems_task_delete( RTEMS_SELF );  
> which in turn, at some point calls 
> rtems_task_variable_delete(RTEMS_SELF, ... ); 
> The same behavior can be reproduces with a slightly modified version 
> of 'ticker test'  
> Adding a task variable pointing to malloc'ed space, assign different values 
> etc. and deleting this space manually after 'rtems_task_variable_delete' 
> everything works Ok. Passing 'free' to automatically delete this space, it 
> ends up in the BSP panic handler.
> Did anybody experienced the same/similar problem? Or, even better, 
> has a fix or work-around? 

Yes I have seen a similar problem with the Telnetd and 

My solution was to remove the rtems_task_variable from the shell!

Not a particularly good solution. This was with 4.5.0 so I was assuming
that I had caused the problem by using a current version of the telnetd
code with an old version of rtems.



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