grsecurity forums

I tried to run the following simple code.

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#include <stdio.h>

unsigned long get_esp() { __asm__("movl %esp, %eax"); }

int main()
{
    printf("esp: %x\n", get_esp());
    return 0;
}

Under RedHat 9 with Gcc 3.2.2, The value of esp reigsters varied as follows;

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[XXX@XXX util]$ ./esp
esp: bfffe5a8
[XXX@XXX util]$ ./esp
esp: bffff028
[XXX@XXX util]$./esp
esp: bfffdca8
[XXX@XXX util]$ ./esp
esp: bfffeca8
[XXX@XXX util]$ ./esp
esp: bfffdd28
[[XXX@XXX util]$ ./esp
esp: bfffe928

Is this the effect of the PaX???
Viewing the object code itself is not special. I think that the compiler
does not affect for the above. When I replaced the kernel, the result
were static.

In RedHat 9, the dynamic stack is default??? And the technology
is from the gresecurity?? This is my question.

(Soooo sorry for my bad English )

phantomforce wrote:Is this the effect of the PaX???

http://pageexec.virtualave.net/docs/randustack.txt, in particular, the third paragraph in the implementation section.