[Python] `call_tabular_function()` segfaults for some wrong typed `func_registry` values

[marinelay]

Describe the bug, including details regarding any error messages, version, and platform.

Summary

The behavior of pyarrow.compute.call_tabular_function() depends on the value supplied as a wrong typed func_registry.

Some values, including 0.0, 1, and -1, terminate the interpreter with SIGSEGV.
Most other tested wrong type values do not crash and instead reach the normal missing function ArrowKeyError path.

I think all non-FunctionRegistry values should be handled consistently without terminating the process, preferably by raising TypeError.

I found this while fuzzing Python C extension modules.

Versions

PyArrow 25.0.0, CPython 3.12.3, Ubuntu 24.04 x86_64, glibc 2.39.

Reproducer

import pyarrow.compute as pc

pc.call_tabular_function("", None, 0.0)

Segmentation fault (core dumped)

Input validation behavior

I kept the function name and args=None unchanged and independently varied only func_registry on the same binary wheel.

Result	Tested func_registry values
SIGSEGV	True, 1, -1, 0.0, 1j, dict
ArrowKeyError from the missing function name	None, False, 0, inf, nan, 0j, str, bytes, bytearray, list, tuple, set,object()

ASan/UBSan result

An earlier instrumented variant using the same wrong-typed registry path reported a misaligned member call in CallTabularFunction():

pyarrow/src/arrow/python/udf.cc:655:3: runtime error:
member call on misaligned address 0x00010c3298eb
for type 'arrow::compute::FunctionRegistry', which requires 8 byte alignment

    #0 arrow::py::CallTabularFunction(...)
       pyarrow/src/arrow/python/udf.cc:655:3
    #1 pyarrow._compute.call_tabular_function(...)
       build/_compute.cpp:70892:92

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
pyarrow/src/arrow/python/udf.cc:655:3

The sanitizer process exits with code 1 at the first UBSan diagnostic.
ASan does not emit a separate diagnostic when UBSan is configured to stop at that first error.

Component(s)

Python