[issue22733] MSVC ffi_prep_args doesn't handle 64-bit arguments properly

[Steve Dower]

New submission from Steve Dower:

The ffi_prep_args function in libffi_msvc/ffi.c needs the attached patch to handle 64-bit parameters with the correct padding.

Without this patch, garbage may appear in the top part of 64-bit arguments as the values are not zeroed out by the memcpy.

I'm not 100% sure who 'owns' this file - is there an upstream project that should get the patch rather than Python? If not, I see no reason not to check this in now, even though it doesn't seem to repro with the VC10 builds.

----------
components: ctypes
files: ffi_prep_args.patch
keywords: patch
messages: 230036
nosy: amaury.forgeotdarc, belopolsky, meador.inge, steve.dower
priority: normal
severity: normal
stage: patch review
status: open
title: MSVC ffi_prep_args doesn't handle 64-bit arguments properly
versions: Python 3.5
Added file: http://bugs.python.org/file37023/ffi_prep_args.patch

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<http://bugs.python.org/issue22733>
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