Set the stack index of the double fault IDT entry

src/interrupts/mod.rs

@@ -10,7 +10,10 @@ lazy_static! {
     static ref IDT: Idt = {
         let mut idt = Idt::new();
         idt.breakpoint.set_handler_fn(breakpoint_handler);
-        idt.double_fault.set_handler_fn(double_fault_handler);
+        unsafe {
+            idt.double_fault.set_handler_fn(double_fault_handler)
+                .set_stack_index(DOUBLE_FAULT_IST_INDEX as u16);
+        }
         idt
     };
 }