Re: non-executable stack (via PT_GNU_STACK) not being enforced

[Goswin von Brederlow <goswin-v-b@web.de>]

Brchk05 <brchk05@aim.com> writes:

> I am running Debian 2.6.26-21lenny4 and I am puzzled by an issue with the
> enforcement of page permissions.  I have written a simple program with a basic
> buffer overflow and compiled two versions using gcc: one with -z execstack and
> another with -z noexecstack.  
>
> So, to verify that the option takes:
>
> For the -z execstack version:
> $ readelf -l a.out | grep -i -A1 stack
>   GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4
>
> For the -z noexecstack version:
> $ readelf -l a.out | grep -i -A1 stack
>   GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x4
>
> However, I am able to inject and execute shellcode from a stack local character
> buffer in both versions.  Is there another system option I am unaware of that
> affects enforcement?  Is enforcement not supported for my system version?
>
> Thanks for your help.

Could you provide source? I'm interested in checking this for my system
too.

MfG
        Goswin