Re: Virtual addresses below 0x8048000

[srinivasa DS <srinivasa.ds@xxxxxxxxx>]

Mulyadi Santosa wrote:
> Hi all..
>
> On Tue, May 20, 2008 at 8:03 PM, srinivasa ds <srinivasa.ds@xxxxxxxxx> wrote:
>   
> > If you use  -pie(position independent executable) option of gcc, load
> > address will be randomly picked. Hence doesn't remain 0x8048000.
> >     
>
> thanks for reminding me about PIE...i forgot that term...grrrr
>
>   
> > Address space randomization is also known as exec-shield in linux, And this
> > is responsible for mapping userspace stack and heap at different address for
> > each execution of same executable.
> >     
>
> nope, exec shield, to the best I know, did the thing like making stack
> non executable or effectively applying NX bit if it's supported by
> your processor. Address space randomization is something separate from
> exec-shield...
>   
Let me dig more information on this....
>   
> > You can even randomize the loading address of the executable using -pie flag
> > in GCC.
> >     
>
> AFAIK, true. However, the loader must also regards this feature...if
> not, you'll be ended in same start address. So it's a collaboration of
> compiler, linker and loader ...CMIIW people
>
>   
Yes, Thats correct.

Thanks
Srinivasa Ds



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