Re: iSeries buffer overflow immunity?

Correct, you cannot assume that admin_flag0 and admin_flag1 are physically
located around buffer.  Defining them as subfields within a data structure
would.

I used your definitions and defined some integer fields (diff1 and diff2).
diff1 = %addr(Buffer) - %addr(admin_flag0) resulted in 8; diff2 =
%addr(admin_flag1) - %addr(Buffer) resulted in -7.  This suggests that with
my current release, PTF level, etc. that storage has been laid out as
admin_flag0, admin_flag1, filler, buffer.   You cannot however rely on this
-- a PTF and recompile of your program, or recompiling on a different
release, could alter all of this...

Bruce



                                                                           
             Rich Duzenbury                                                
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                                       Re: iSeries buffer overflow         
             11/05/2004 11:16          immunity?                           
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That's what I had initially thought, too, but my experimental code did
not fail:

D admin_flag0     s              1    inz('N')
D buffer          s              5
D admin_flag1     s              1    inz('N')

D ptr             s               *
D memory          s              6    based(ptr)
 /free
     ptr = %addr(buffer);
     memory = '12345Y';

     if admin_flag0 = 'Y' or admin_flag1 = 'Y';
         dsply 'Uh-Oh';
     endif;
     *inlr = '1';
 /end-free

What did I do wrong?  Can I not be sure that the admin_flag0 and
admin_flag1 are located next to the unprotected buffer?