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python: backport gh-157579 (CVE-2026-12345, tempfile cleanup race) to 3.14.8 - #895
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… 3.14.8 TemporaryDirectory cleanup re-resolved paths while resetting permissions, so an attacker able to modify the tree during cleanup could swap a directory for a symlink and have files outside the temporary directory removed (PSF-2026-42). Carry upstream's own 3.14 backport (python/cpython#158430, merge 58ed0259, merged 2026-10-09, after 3.14.8) byte-for-byte; it applies at fuzz 0 to 3.14.8 and touches none of the files 0002/0003 change. Regression test tempfile_cleanup_race_fix: fails on stock 3.14.8 (no dir-fd cleanup, no rmtree onexc kwargs), passes with the patch, and checks a read-only subtree still cleans up completely. We stay on the 3.14 series (pkgs#891 closed: node-lts's configure rejects Python 3.15); this was the one advisory 3.15.0 fixed that 3.14.8 lacked. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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The title clearly identifies the main change: backporting the gh-157579 tempfile cleanup race fix to Python 3.14.8. |
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norrietaylor
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LGTM. The patch is identical to the upstream 3.14 backport 58ed0259 (GH-158430); only the hunk-header context differs. It's not in v3.14.8, applies cleanly, and is wired in before configure.
Nit, build.ncl:353: os.chmod(sub, S_IRUSR|S_IXUSR) won't force the permission-reset path if tests run as root. The presence checks still keep the test meaningful.
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classpath-0.93 failed on pkgs#895 (a python-only change) with
`sort: /usr/lib/libc.so.6: version GLIBC_2.43 not found`. The rungs
depend on the whole glibc-bedrock-2.42, and its sealed amd64 tarball
carries a full glibc 2.42 at /usr/lib (listed: usr/lib/libc.so.6,
ld-linux-x86-64.so.2, 4087 entries), whatever its output globs say. That
collides with production glibc 2.44 path for path (~1400 files); the
sandbox keeps whichever lands first ("Not linking ... already exists"),
which shifts with fetch timing, so an unrelated python change flipped
classpath's /usr/lib/libc.so.6 to 2.42 and every production tool in the
sandbox stopped loading.
The new glibc-bedrock-2.42-sysroot collection carries only
usr/lib/glibc-bedrock-2.42/{lib,include}, all the rungs use (SR=), and
the 28 rungs import it in place of glibc-bedrock-2.42. A collection
because `subsetOf` is only supported in runtime_deps: in build_deps it
panics minimal's executor (op/src/specs.rs:88, todo!), which is what
stopped #937.
Verified on the lab (amd64, mip): main + #895's python + this builds
jikes-1.22 and classpath-0.93 (rc=0), with no glibc path conflict in
classpath's sandbox; without it, the same tree reproduces the failure.
Rebuilds the amd64 JVM ladder once.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This was referenced Oct 20, 2026
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….2.2 swap main gained #941 (JVM ladder takes only the bedrock sysroot; the classpath glibc collision that failed #950's amd64 leg) and #895 (gh-157579 patch), which conflicted here only by adding beside this PR's pip wheel. Both kept: the 0004 patch with the other patches, then the ensurepip wheel swap. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This was referenced Oct 22, 2026
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Why
We're staying on Python 3.14 for now. #891 (→ 3.15.0) is closed because the released node-lts
configurerejects Python 3.15 and the bump rebuilds 100+ packages. Of the 3 advisories 3.15.0 cleared, 3.14.8 already carries patches for two (poplib gh-143923, tarfile gh-157265). This PR covers the third:CVE-2026-12345 / PSF-2026-42 (MEDIUM), gh-157579.
tempfile.TemporaryDirectorycleanup re-resolved paths while resetting permissions. An attacker who can modify the tree during cleanup can replace a directory with a symlink and cause files outside the temporary directory to be removed.What
0004-gh-157579-tempfile-cleanup-race.patchis upstream's own 3.14 backport: [3.14] gh-157579: Fix race condition in the cleanup oftempfile.TemporaryDirectory(GH-157580) python/cpython#158430, merge58ed0259, merged to 3.14 on 2026-10-09, after 3.14.8 was cut. It is carried byte-for-byte.patch -p1 -N -F0 --dry-run).build.shapplies it the same fail-closed way as 0002/0003.build.nclcomment records where it came from, plus the drop condition: the first 3.14.x whose changelog lists gh-157579, which should be 3.14.9. From now on pkgmgr's updater checks this itself and removes patches that are already upstream (pkgmgr-rs#988).Test
tempfile_cleanup_race_fix(Standalone). The race itself can't be reproduced deterministically, so the test guards the fix's presence and normal behaviour:tempfile._rmtree_use_dir_fdis True, meaning cleanup works relative to open directory fds;shutil.rmtreehas the_onexc_kwargsparameter;I checked the test script locally with Python 3.14 against the stock and patched
tempfile.py/shutil.py: stock fails (both presence checks), patched passes. This was not a package build; CI/buildbot will build it.🤖 Generated with Claude Code
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