Working PS/2 keyboard driver

kernel/device/terminal.c

@@ -43,6 +43,9 @@ int terminal_putstr (struct proc* proc, void* a1, void* a2, void* a3, void* a4)
   char* string = (char*)a1;
   size_t* len = (size_t*)a2;
 
+  if (string == NULL || len == NULL)
+    return -ST_BAD_ADDRESS_SPACE;
+
   flanterm_write (ft_ctx, string, *len);
 
   return ST_OK;