Karl Nelson <[email protected]> added the comment:
I will look through the list of samples in Detours to see if there is something
that can give us better stacktrace information. If we really need a stack
trace I can make Detours bust by creating an intentional segfault and see if we
can attach the debugger after the source of the problem has been triggered.
Unfortunately as my windows programming knowledge is all from 1994 I may be
missing something obvious.
In the meantime I am upgrading the sample with some more hooks for any other
potential LoadLibrary variants and FlsGetValue. Though given the
GetProcAddress calls I think that it must be something in the chain leading up
so the variants are likely not envolved.
The other thing I can do is look at instrumenting SetErrorMode so that I can
give myself a marker of when we are entering and leaving the dyload code.
```
/* Don't display a message box when Python can't load a DLL */
old_mode = SetErrorMode(SEM_FAILCRITICALERRORS);
/* bpo-36085: We use LoadLibraryEx with restricted search paths
to avoid DLL preloading attacks and enable use of the
AddDllDirectory function. We add SEARCH_DLL_LOAD_DIR to
ensure DLLs adjacent to the PYD are preferred. */
Py_BEGIN_ALLOW_THREADS
hDLL = LoadLibraryExW(wpathname, NULL,
LOAD_LIBRARY_SEARCH_DEFAULT_DIRS |
LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR);
Py_END_ALLOW_THREADS
#if !USE_UNICODE_WCHAR_CACHE
PyMem_Free(wpathname);
#endif /* USE_UNICODE_WCHAR_CACHE */
/* restore old error mode settings */
SetErrorMode(old_mode);
```
I will post back once I get some results.
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<https://bugs.python.org/issue42529>
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