[3.12] gh-112334: Restore subprocess's use of vfork() & fix extra_groups=[] behavior (GH-112617)
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…roups=[]` behavior (pythonGH-112617) Restore `subprocess`'s intended use of `vfork()` by default for performance on Linux; also fixes the behavior of `extra_groups=[]` which was unintentionally broken in 3.12.0: Fixed a performance regression in 3.12's :mod:`subprocess` on Linux where it would no longer use the fast-path ``vfork()`` system call when it could have due to a logic bug, instead falling back to the safe but slower ``fork()``. Also fixed a security bug introduced in 3.12.0. If a value of ``extra_groups=[]`` was passed to :mod:`subprocess.Popen` or related APIs, the underlying ``setgroups(0, NULL)`` system call to clear the groups list would not be made in the child process prior to ``exec()``. The security issue was identified via code inspection in the process of fixing the first bug. Thanks to @vain for the detailed report and analysis in the initial bug on Github. (cherry picked from commit 9fe7655) Co-authored-by: Gregory P. Smith <greg@krypto.org> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
3 tasks
(mentions the assigned CVE number)
gpshead
approved these changes
Dec 4, 2023
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Restore
subprocess's intended use ofvfork()by default for performance on Linux;also fixes the behavior of
extra_groups=[]which was unintentionally broken in 3.12.0:Fixed a performance regression in 3.12's :mod:
subprocesson Linux where itwould no longer use the fast-path
vfork()system call when it could havedue to a logic bug, instead falling back to the safe but slower
fork().Also fixed a security bug introduced in 3.12.0. If a value of
extra_groups=[]was passed to :mod:
subprocess.Popenor related APIs, the underlyingsetgroups(0, NULL)system call to clear the groups list would not be madein the child process prior to
exec().The security issue was identified via code inspection in the process of
fixing the first bug. Thanks to @vain for the detailed report and
analysis in the initial bug on Github.
(cherry picked from commit 9fe7655)
Co-authored-by: Gregory P. Smith greg@krypto.org
Co-authored-by: Serhiy Storchaka storchaka@gmail.com
The security issue has been assigned CVE-2023-6507.