gh-156204: Guard recursion in PyErr_GivenExceptionMatches by BHUVANSH855 · Pull Request #156205 · python/cpython · GitHub

Fixes issue gh-156204.

PyErr_GivenExceptionMatches in Python/errors.c recursively unpacks tuple targets without recursion checks, causing native C stack exhaustion and a SIGSEGV when given deeply nested exception tuples.

This change:

Guards recursion in PyErr_GivenExceptionMatches via Py_EnterRecursiveCall() and Py_LeaveRecursiveCall().
Adds a _testcapi.err_givenexceptionmatches() helper and a regression test in Lib/test/test_exceptions.py.
Adds a blurb NEWS entry.

Verified: with Python/errors.c reverted to the pre-fix version the new test segfaults; with the fix it passes.

…ple depth

Documentation build overview

📚 cpython-previews | 🛠️ Build #34178190 | 📁 Comparing b6be6c5 against main (999a046)

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2 files changed
± c-api/exceptions.html
± whatsnew/changelog.html

Looks like some test is failing.

…tion-matches-recursion

Looks like some test is failing.

hi, the failing checks were unrelated to this PR, as the PR was stale form some days, so I updated the branch and synced it to the current main.
Hope this time no check fails.

LGTM. I'll give Irit some time to take another look before merging, and I'll also run the buildbots in the meantime to make sure that the recursive test doesn't fail on some weird platforms.

🤖 New build scheduled with the buildbot fleet by @ZeroIntensity for commit 141b181 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F156205%2Fmerge

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Thanks @BHUVANSH855 for the PR, and @ZeroIntensity for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖

GH-158622 is a backport of this pull request to the 3.15 branch.

GH-158623 is a backport of this pull request to the 3.14 branch.

…H-156205) (GH-158623) (cherry picked from commit 20d5e67) Co-authored-by: Bhuvansh <bhuvanshkataria@gmail.com>

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HEAD is now at a9eeb9f2f51 [3.14] gh-156204: Guard recursion in `PyErr_GivenExceptionMatches` (GH-156205) (GH-158623)
Switched to and reset branch '3.14'

Could Not Find C:\bbarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\Lib\*.pyc
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Could Not Find C:\bbarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\PCbuild\python*.zip

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Could Not Find C:\bbarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\PCbuild\python*.zip

Expanding reachable commits in commit graph: 138558
Expanding reachable commits in commit graph: 171624, done.

pythongh-156204 : Guard recursion in PyErr_GivenExceptionMatches

df43d6a

BHUVANSH855 requested a review from iritkatriel as a code owner August 21, 2026 18:59

bedevere-app Bot added the awaiting review label Aug 21, 2026

bedevere-app Bot mentioned this pull request Aug 21, 2026

PyErr_GivenExceptionMatches crashes with SIGSEGV on deeply nested tuple targets #156204

Closed

pythongh-156204 : Safely skip ctypes test on mobile/wasm and reduce tu…

d0d8595

…ple depth

iritkatriel reviewed Aug 21, 2026

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Comment thread Lib/test/test_exceptions.py Outdated

iritkatriel reviewed Aug 21, 2026

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Comment thread Misc/NEWS.d/next/Core_and_Builtins/2026-08-21-18-49-12.gh-issue-156204.ZusA7e.rst Outdated

pythongh-156204 : address review feedback

b6be6c5

BHUVANSH855 requested a review from ZeroIntensity as a code owner August 21, 2026 20:16

BHUVANSH855 requested a review from iritkatriel August 21, 2026 20:17

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Comment thread Doc/c-api/exceptions.rst Outdated

pythongh-156204 : drop docs change

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BHUVANSH855 requested a review from ZeroIntensity August 21, 2026 20:29

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Comment thread Modules/_testcapi/exceptions.c Outdated

Comment thread Python/errors.c

pythongh-156204 : convert test helper to Argument Clinic

12ce58f

BHUVANSH855 requested a review from iritkatriel September 24, 2026 14:12

pythongh-156204 : remove comment

e7c80b9

BHUVANSH855 added 2 commits September 27, 2026 10:35

Merge remote-tracking branch 'upstream/main' into fix-err-given-excep…

a4fc16a

…tion-matches-recursion

Merge branch 'main' into fix-err-given-exception-matches-recursion

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ZeroIntensity reviewed Sep 27, 2026

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Comment thread Python/errors.c

Comment thread Modules/_testcapi/exceptions.c Outdated

Comment thread Python/errors.c Outdated

pythongh-156204 : report recursion overflow as unraisable

141b181

BHUVANSH855 requested a review from ZeroIntensity September 27, 2026 18:49

ZeroIntensity reviewed Sep 28, 2026

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Comment thread Python/errors.c

ZeroIntensity approved these changes Sep 28, 2026

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bedevere-app Bot added awaiting merge and removed awaiting review labels Sep 28, 2026

ZeroIntensity added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 28, 2026

bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Sep 28, 2026

ZeroIntensity added needs backport to 3.14 bugs and security fixes needs backport to 3.15 pre-release feature fixes, bugs and security fixes labels Oct 2, 2026

ZeroIntensity merged commit 20d5e67 into python:main Oct 2, 2026
144 of 150 checks passed

bedevere-app Bot removed the awaiting merge label Oct 2, 2026

bedevere-app Bot removed the needs backport to 3.15 pre-release feature fixes, bugs and security fixes label Oct 2, 2026

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Oct 2, 2026

ZeroIntensity pushed a commit that referenced this pull request Oct 2, 2026

[3.14] gh-156204 : Guard recursion in PyErr_GivenExceptionMatches (G…

a9eeb9f

…H-156205) (GH-158623) (cherry picked from commit 20d5e67) Co-authored-by: Bhuvansh <bhuvanshkataria@gmail.com>

BHUVANSH855 deleted the fix-err-given-exception-matches-recursion branch October 3, 2026 05:46

This was referenced Oct 3, 2026

Doc: Py_EnterRecursiveCall uses C stack space, not a call counter #158643

Closed

gh-158643: Doc: document that Py_EnterRecursiveCall uses C stack, not a counter #158644

Merged

gh-156204: Guard recursion in PyErr_GivenExceptionMatches by BHUVANSH855 · Pull Request #156205 · python/cpython · GitHub

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gh-156204: Guard recursion in PyErr_GivenExceptionMatches - #156205

gh-156204: Guard recursion in PyErr_GivenExceptionMatches#156205ZeroIntensity merged 9 commits intopython:mainpython/cpython:mainfrom BHUVANSH855:fix-err-given-exception-matches-recursionBHUVANSH855/cpython:fix-err-given-exception-matches-recursionCopy head branch name to clipboard

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gh-156204: Guard recursion in PyErr_GivenExceptionMatches#156205
ZeroIntensity merged 9 commits into
python:mainfrom
BHUVANSH855:fix-err-given-exception-matches-recursion

BHUVANSH855 commented Aug 21, 2026 •
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