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itsmattkc / dotnet9x

Backport of .NET 2.0 - 3.5 to Windows 9x
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Thread::SuspendThread and ResumeThread will probably crash .NET apps that use them #14

Open pub31415 opened 7 months ago

pub31415 commented 7 months ago

Great work on the backport and the "movie" about it!

I wrote a whole blogpost about what ndphlpr.vxd does lel Since the project intercepts the call to DeviceIoControl and forces OutBuffer to 0x40 while ndphlpr.vxd is not really loaded, mscorwks.dll will try to use non-functional APIs for Thread::SuspendThread and ResumeThread

https://pub31415.bearblog.dev/what-ndphlprvxd-does/

I cant test it though, since I dont have .NET on me.

itsmattkc commented 7 months ago

Hey thanks for the writeup! Now something will finally show up when you google it ;)

I have indeed been made aware of NDPHLPR's true purpose since posting the video (there are also references in leaked Windows code that make its usage clear that I won't link here), and yes you're probably right the hack I've implemented will presumably cause thread issues in the long-term.

So I guess the question remains - why doesn't NDPHLPR.VXD load on Windows 95 and what can be done to resolve that?

IntriguingTiles commented 7 months ago

why doesn't NDPHLPR.VXD load on Windows 95

per this thread:

in the control routine, on initialisation, there's a version check, against 4.10 (ie, windows 98)

cargoudel commented 7 months ago

If NDPHLPR.VXD can be patched to remove the 98 check or even just make NDPHLPR.VXD stub for the Windows/... folder so it will load correctly. I wonder what modern windows does with this check, anyway?

ZhaoZhen711 commented 7 months ago

If NDPHLPR.VXD can be patched to remove the 98 check or even just make NDPHLPR.VXD stub for the Windows/... folder so it will load correctly. I wonder what modern windows does with this check, anyway?

My guess is Windows for weird architectures that don't support multi-tasking/multi-threading. I would bet that Windows XP Embedded and NT 4.0 Embedded would still have the check, not sure if the modern Embedded/IoT version would still have it. Possibly Windows for ARM.

beigexperience commented 7 months ago

leaked Windows code that make its usage clear that I won't link here

Don't keep us in the dark. What was the purpose of the driver?