Python 3.13 refcounting related memory corruption

[Florian Bruhin]

> On 28/05/2024 17:04, Florian Bruhin wrote:
> >> Unfortunately I've not been able to extract a minimal example by any
> >> means. The best I could get is getting it down to running 11 test 
> >> files
> >> in qutebrowser, with almost 2000 test cases. If I remove any of those
> >> files, the bug doesn't trigger anymore.
> > 
> > I've been able to reduce this to a minimal example now, which is
> > attached and (at least for me) crashes reliably with Python 3.13.
> > 
> > Florian
> 
> I can't get it to crash on either macOS or Linux.

I was only trying the minimal example with ASan enabled, i.e. with
CPython built with:

    $ export CC="/usr/bin/clang -fsanitize=address"
    $ ./configure --with-address-sanitizer  --without-pymalloc --with-pydebug

The attached revised example seems to crash more reliably with a vanilla
CPython.

If that doesn't work, try with PYTHONMALLOC=malloc (no Python rebuild
needed).

If that still doesn't work, rebuild Python as above, or try under
valgrind:

    PYTHONMALLOC=malloc valgrind python3.13 py313_crash_v2.py

Florian
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