ntdll:exception crashes some Windows 10

[Francois Gouget]

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 :-(


-- 
Francois Gouget <fgouget at codeweavers.com>