Re: Virtual addresses below 0x8048000

["Mulyadi Santosa" <mulyadi.santosa@xxxxxxxxx>]

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...

> 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

regards,

Mulyadi.

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