SharedUnixLibrary and the System Heap

Matt Edgar matt at stdevel.co.uk
Mon Mar 27 15:58:49 PST 2006


John Tytgat wrote:

>>Switching to a privledged mode within SUL in order to access the heap 
>>seems like a sensible solution.
>> 
> I wasn't aware that there is code in the SUL module itself executed in
> user mode accessing the SVC stack (that's what you are saying, isn't it ?).
> 
> You're sure it is SUL module code and not UnixLib in application space ?

Yes.

For example:

The penultimate instruction of function |delink| is STR R0,[R1,#0] where 
R1 points into the System Heap.

The problem here is that |delink| is called from the program's exit 
handler, which executes in USR mode.

> I'm willing to investigate this more but I presume you have something I
> can use to protect the system heap from user mode access and see where
> things are breaking ?

Thank you, I'll see what I can sort out.

Matt




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