retitle 884705 python3-cffi-backend: does not handle pointers on ILP32 ABIs
correctly
reassign 884705 python3-cffi-backend
found 884705 1.11.5-1+b1
affects 884705 src:python-cryptography
# remove those, as they were for python-cryptography
notforwarded 884705
tags 884705 = patch
thanks
Please see the following thread (former forwarded-to) for more debugging:
https://github.com/pyca/cryptography/issues/4078
I discovered that cffi’s mechanism to zero- or sign-extend values
smaller than the CPU register size (ffi_arg) was only applied to
signed or unsigned integer values but not pointers, whereas the
x86-64 (amd64 and x32) ELF psABI specifies that 32-bit pointers
passed in 64-bit registers must be zero-padded.
Some architectures might require sign-padding them instead, but
considering that x32 appears to be the first one actually running
into this issue I’d default to zero-pad them on all architectures.
The extra code path will only ever be triggered on 64-bit ILP32
architectures, which are basically all new (unless MIPS n32 was
one of them, but I don’t think so, or they’d have been hit from
this bug).
Please forward this upstream and apply it in Debian, to make
packages that use cffi work reliably on x32.
Thanks,
//mirabilos
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--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -5636,6 +5636,7 @@ static int convert_from_object_fficallba
return 0;
}
else if (ctype->ct_flags & (CT_PRIMITIVE_CHAR | CT_PRIMITIVE_SIGNED |
+ CT_POINTER | CT_FUNCTIONPTR |
CT_PRIMITIVE_UNSIGNED)) {
/* zero extension: fill the '*result' with zeros, and (on big-
endian machines) correct the 'result' pointer to write to */
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