[Bug 40479] Overwatch: Crash on launch

[wine-bugs at winehq.org]

https://bugs.winehq.org/show_bug.cgi?id=40479

--- Comment #9 from Matteo Bruni <matteo.mystral at gmail.com> ---
Created attachment 54443
  --> https://bugs.winehq.org/attachment.cgi?id=54443
Hack for the first crash

It's indeed crashing in the second TLS callback for me too. It turns out that
it wants to copy the entire dxgi.dll image in memory to a separate buffer and
that throws an EXCEPTION_ACCESS_VIOLATION while reading. That's because (for me
at least) there is a ~2MB memory area inside the DLL image with no access
permissions. Just adding read permissions there doesn't work, probably because
the mmapped area is larger than the size of the file on disk. The attached hack
unmaps that area and creates an anonymous mapping in its place and that
apparently avoids this first crash. I'm not sure what I'm exactly unmapping and
what it entails...

With the hack the game still crashes soon after that. There is a third TLS
callback which is run after setting a vectored exception handler. This callback
is in a memory area with no read or execute permissions so the call immediately
causes an exception. The exception handler sets the read and execute
permissions for the first page of the callback code and resumes its execution.
Soon after there is another exception when trying to execute the first
instruction crossing the page boundary. This time though the exception handler
doesn't change the page protection nor resume execution so the game crashes.

I imagine the exception handler doesn't like something about the exception, or
that second exception isn't supposed to happen at all (i.e. the callback code
should take a different path). No idea at this point. I tried to modify the
exception info more or less arbitrarily but with no luck.

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