[issue43142] Do not add duplicate FDs to list in duplicate_for_child()
New submission from Sanchit : While spawning, if a process having code built on top of Python's multiprocessing module calls multiprocessing.reduction.DupFd() (in /Lib/multiprocessing/reduction.py) multiple times on the same File descriptor by mistake, then it ends up invoking duplicate_for_child(fd)) of the class Popen, which, in turn, adds a duplicate FD to a list. This list is then used in spawnv_passfds() in /Lib/multiprocessing/util.py, which uses that list as an argument in a call of _posixsubprocess.fork_exec(). In Modules/_posixsubprocess.c, checks exist to ensure that all the FDs in the list are unique, positive, and in a sorted order. If duplicate entries are found, a ValueError: bad value(s) in fds_to_keep exception is raised, and the execution is terminated. Even if this exception were somehow handled, a developer can't change the aforementioned FD list in Python without breaking modularity. It's better to let developers get away with calling multiprocessing.reduction.DupFd() (in /Lib/multiprocessing/reduction.py) on by not accepting duplicate entries in the first place, so that spawning a process can be successful. -- components: Library (Lib) messages: 386546 nosy: sanchit priority: normal severity: normal status: open title: Do not add duplicate FDs to list in duplicate_for_child() type: behavior versions: Python 3.10, Python 3.6, Python 3.7, Python 3.8, Python 3.9 ___ Python tracker <https://bugs.python.org/issue43142> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43142] Do not add duplicate FDs to list in duplicate_for_child()
Change by Sanchit : -- keywords: +patch pull_requests: +23257 stage: -> patch review pull_request: https://github.com/python/cpython/pull/24461 ___ Python tracker <https://bugs.python.org/issue43142> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43142] Do not add duplicate FDs to list in duplicate_for_child()
Sanchit added the comment: But can you please add this fix in versions 3.8 & beyond? Thanks! From: report=bugs.python@roundup.psfhosted.org on behalf of Terry J. Reedy Sent: Friday, February 12, 2021 3:43 PM To: SANCHIT JAIN Subject: [issue43142] Do not add duplicate FDs to list in duplicate_for_child() Terry J. Reedy added the comment: 3.7 and before only get security fixes. -- nosy: +davin, pitrou, terry.reedy versions: -Python 3.6, Python 3.7 ___ Python tracker <https://bugs.python.org/issue43142> ___ -- ___ Python tracker <https://bugs.python.org/issue43142> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue21063] Touch up one-line descriptions of modules for module index
Change by Sanchit Khurana : -- pull_requests: +16848 stage: needs patch -> patch review pull_request: https://github.com/python/cpython/pull/17363 ___ Python tracker <https://bugs.python.org/issue21063> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
