Re: Protecting my application from memory problems

[Charles Wilt <charles.wilt@xxxxxxxxx>]

Per the ILE concepts manual...

An activation group contains the following resources...
- Static program variables
- Dynamic storage
- Temporary data management resources
- Certain types of exception handlers and ending procedures

So I'd say yes, it should be helpful to have your program in it's own
activation group in the scenario you gave.

But I suspect one of the main causes of memory corruption is parameter
mismatches.  If your code is calling anybody else code I think it'd be
possible for the other code to corrupt your memory space...even with
different activation groups.

I suspect if you really want to protect your code, you'd have to build it
as a service running in the background using data queues or sockets to
communicate to other programs.

It'd be interesting to hear from others with a better understanding of the
internals...

Charles



On Tue, Mar 31, 2015 at 11:58 AM, Zachary Johnson <ZJohnson@xxxxxxxxxxxxx>
wrote:

> Hi all,
>
> Is there a way that I can protect my application from other programs down
> the line doing memory over writes.  Separate activation groups will
> separate the heaps but I'm not 100% certain this will solve my problem
> because of SLS.
>
> Here is a scenario, assume these are using the default SLS heap.  PGMA is
> my app and PEP and PGMB is another app that I am calling:
>
> PGMA   running activation group 'GROUP1'
>     Calls PGMB activation group *CALLER.
>
> If PGMB does something like
>
> D value        s           20a  Based(ptr)
> ptr = %Alloc(10) ;
> Clear value;
> Return;
>
> This potentially causes PGMA to fail (through no fault of his own) due to
> the memory over write.  I'm thinking I can use a different activation group
> to protect myself from PGMB doing something stupid.  He may fail eventually
> but it won't affect PGMA.
>
> PGMA activation group 'GROUP1'
>   Calls PGMA1 activation group 'GROUP2'
>         Calls PGMB activation group *CALLER.
>
> This would create a boundary between PGMA and PGMB right?
>
>
> Thanks for any input.
>
> Zach
>
>
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