Very Computer

1. double the buffer? - buffer overflows

Hey,

I'm a novice programmer reading up on buffer overflows in order to secure
my own programs for exploitation. While reading over "Smashing The Stack
For Fun And Profit" (from phrack #49) i came accross the following
discrepancy on a standard workstation install of redhat 7.2 (gcc 2.96): I
complile this:

example1.c:
------------------------------------------------------------------------------
void function(int a, int b, int c) {
   char buffer1[5];
   char buffer2[10];
void main() {
  function(1,2,3);
------------------------------------------------------------------------------

with gcc -S -o example1.s example1.c

and instead of

        pushl %ebp
        movl %esp,%ebp
        subl $20,%esp

i have

        pushl   %ebp
        movl    %esp, %ebp
        subl    $40, %esp

under the function call. My question is: Why? Is this something redhat
specific? is this something gcc specific? is this the standard on most
linux (or even *nix) systems? I realise the article is a bit dated, but
having a buffer double the size caught be off guard.

Your insight would be greatly appreciated, Thanks. :)

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