Catching STATUS_ASSERTION_FAILURE with SEH on Insider builds?

NTDEV
1

We've got a kernel-mode test suite (so this is all about code used internally and never shipped to customers) which contains some tests of the form "if MyInternalRoutine is called with <these invalid parameters>, then an assertion, i.e. via the NT_ASSERT macro, is raised". This is achieved by wrapping the call in a SEH frame, in the end it looks like this:

NTSTATUS caught = STATUS_SUCCESS;
__try {
    MyInternalRoutine(NULL); // NULL here is an invalid parameter
}
__except (EXCEPTION_EXECUTE_HANDLER) {
    caught = GetExceptionCode();
}
if (caught == STATUS_ASSERTION_FAILURE) {
    // Record test success
} else {
    // Record test failure
}

Naturally, building this in DEBUG configuration is required (due to use of NT_ASSERT). This approach works on the generally available versions of Windows client, like 19045, 22631 or 26100 etc. that we've tested.

Last week I was probably the first person to run these against an Insider Preview build of Windows. With the latest canary ring build (27871 at the time) installed, to my surprise got a green screen of death, KMODE_EXCEPTION_NOT_HANDLED, coming from the assert test, from inside MyInternalRoutine.

I've tried replacing the NT_ASSERT with a "write to NULL" primitive - that causes a STATUS_ACCESS_VIOLATION exception which the test setup SEH frame catches successfully. So it looks like the build I have does not let you catch asserts.

Before I start digging I wonder if anyone's encountered this before. My two hypotheses at the moment are:

  1. This is an Insider build special behaviour
  2. This is a change in the next version of Windows and is not specific to Insider builds