[3.14] gh-151519: Check effective gid in _test_all_chown_common group-0 guard (GH-151521)#151550
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…p-0 guard (pythonGH-151521) The guard that skips the "chown to gid 0 should fail" assertion used only `os.getgroups()` (supplementary groups). The kernel also accepts the effective/filesystem gid for chown, so when a process runs with egid 0 and a non-zero uid (common in containers and user namespaces), chown(-1, 0) succeeds and the assertion spuriously fails. Add an `os.getegid() != 0` check alongside the existing `0 not in os.getgroups()` guard. (cherry picked from commit 2ce260033b457a0ad2c9767a1d9902bef5a30b0e) Co-authored-by: Itamar Oren <itamarost@gmail.com>
This was referenced Jun 16, 2026
test_posix._test_all_chown_common ignores the effective gid when checking group-0 membership
#151519
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The guard that skips the "chown to gid 0 should fail" assertion used
only
os.getgroups()(supplementary groups). The kernel also acceptsthe effective/filesystem gid for chown, so when a process runs with
egid 0 and a non-zero uid (common in containers and user namespaces),
chown(-1, 0) succeeds and the assertion spuriously fails.
Add an
os.getegid() != 0check alongside the existing0 not in os.getgroups()guard.(cherry picked from commit 2ce2600)
Co-authored-by: Itamar Oren itamarost@gmail.com