[New-bugs-announce] [issue42655] Fix subprocess extra_groups gid conversion

[Jakub Kulik]

New submission from Jakub Kulik <kulikjak at gmail.com>:

C function `subprocess_fork_exec` incorrectly transforms gids from the `extra_groups` argument because it passes `unsigned long*` rather than `pid_t*` into the `_Py_Gid_Converter()`. Assuming that `gid_t` is 32 bit and `unsigned long` is 64 bit (which it often is), `*(gid_t *)p = gid;` then incorrectly overwrites only part of that variable, leaving the other one filled with previous garbage.

I found this on Solaris, but I am pretty sure that this doesn't work correctly on Linux as well, since both use `unsigned int` as `gid_t`.

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components: Extension Modules
messages: 383132
nosy: kulikjak
priority: normal
severity: normal
status: open
title: Fix subprocess extra_groups gid conversion
versions: Python 3.10, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42655>
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