Can't execute Shellcode --> (Speicherzugriffsfehler (Speicherabzug geschrieben))

i have this function:

char code[] = "\xeb\x19\x31\xc0\x31\xdb\x31\xd2\x31\xc9\xb0\x04\xb3\x01\x59\xb2\x05\xcd\x80\x31\xc0\xb0\x01\x31\xdb\xcd\x80\xe8\xe2\xff\xff\xff\x68\x65\x6c\x6c\x6f";

int main(int argc, char **argv)
{
  int (*func)();
  func = (int (*)()) code;
  (int)(*func)();
}

(this code is from: shellcode tutorial)

so i compiled and execute it, but i only get this message: Speicherzugriffsfehler (Speicherabzug geschrieben).

Why i don't get something back, only this error message?

p.s.: my system is an ubuntu x86 pc. the shellcode should work with it. i compiled it with gcc and with gcc-4.5, both same error...

Solution

By default gcc will compile applications as having nonexecutable stacks. What you're seeing is a segmentation violation because your stack is marked nonexecutable but you're trying to execute code on the stack. You can verify by running your application in gdb and checking where it dies, for instance:

=> 0x601060 : jmp 0x60107b

This is the entry point of your shellcode. To make it so it doesn't segfault, you can disable exectstack by doing the following:

gcc -z execstack source.c