smashing the stack, output of x is not 1, instead still 777

#include "stdio.h"


void function(int a, int b, int c) {
char buffer1[5];
char buffer2[10];
char *ret;

ret = buffer1 + 12;
(*ret) += 8;
}

void main() {
int x;

x = 777;
function(1,2,3);
x = 1;
printf("%d\n",x);
getchar();
}