Description

theosotr

opened on Nov 5, 2026

Issue body actions

Bug report

Summary

Assigning to a ctypes pointer's .contents crashes the interpreter with SIGSEGV if the value is an ordinary Python object that claims to be the right type.

Expected: a TypeError, from a type check that does not consult __class__.

Reproducer

import ctypes

class Forge:
    __slots__ = ("a", "b", "c", "d")
    __class__ = ctypes.c_int

    def __init__(self):
        self.a = ctypes.c_int(7)
        self.b = self.c = self.d = None

ctypes.pointer(ctypes.c_int(1)).contents = Forge()

Segmentation fault (core dumped)

CPython versions tested on:

3.15

Operating systems tested on:

Linux

Linked PRs

• gh-161390: Reject non-ctypes objects assigned to pointer contents #161402

Activity

1. theosotr

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Nov 5, 2026
2. sobolevn

   added

   topic-ctypes

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   and removed

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Nov 5, 2026
3. makwana-akshat commented on Nov 5, 2026

   

   makwana-akshat

   on Nov 5, 2026

   More actions

   i would like to solve this issue. assign/
4. rajorin

   added a commit that references this issue on Nov 5, 2026

   pythongh-161390: Avoid an unresolved contents reference in the NEWS e…

   9815024

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