ntdll:exception crashes some Windows 10

[Paul Gofman]

On 12/8/20 17:39, Francois Gouget wrote:
> On Mon, 7 Dec 2020, Paul Gofman wrote:
>
>> On 12/7/20 17:07, Francois Gouget wrote:
> [...]
>>>     dreg_test.dr0 = 0x42424240;
>>>     dreg_test.dr2 = 0x126bb070;
>>>     dreg_test.dr3 = 0x0badbad0;
>>>     dreg_test.dr7 = 0xffff0115;
>>>     run_exception_test(dreg_handler, &dreg_test, &segfault_code, sizeof(segfault_code), 0);
> [...]
>> While it looks like a definite VM bug, it is maybe interesting to know
>> for a start what exactly triggers the error. Is it possible to see if
>> disabling the setting of the debug registers in dreg_handler() above
>> (lines context->Dr<n> = test->dr<n>;) avoids the crash, and if yes,
>> which exactly register(s) setting trigger that.
> It does not matter which register is set (dr0, dr2, dr3 or dr7), Windows 
> crashes with any of them. It's only if I comment all of them out that it 
> does not crash :-(
>
>
Are you commenting out here in the cited code or (better) in dreg_handler?