GeezerVison is showing github.com — gh-159811: Raise OpenSSL errors in `_hashlib.HMAC` after re-attaching the thread state by picnixz · Pull Request #159818 · python/cpython
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picnixz
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Oct 19, 2026
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hashlib_openssl_HMAC_update_once() set an exception when the OpenSSL HMAC update function failed, but it was called inside a GIL-released region, with the object's mutex held, by _hashlib.HMAC.update() and _hashlib.hmac_new() when the data exceeds HASHLIB_GIL_MINSIZE bytes. Setting the exception with the thread state detached crashes the interpreter instead of raising an exception.
Remove that helper, call the OpenSSL HMAC update function directly in _hmac_update(), and set the exception once the thread state is re-attached and the mutex is released, as it was done before gh-134531. The OpenSSL error queue is per thread, so the exception type and message are unaffected.
This regression was introduced by gh-134531, so only 3.15 needs a backport. The _hashlib.HASH counterpart, which also affects 3.13 and 3.14, is handled in #159817.
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…aching the thread state
`hashlib_openssl_HMAC_update_once()` set an exception when the OpenSSL
HMAC update function failed, but it was called inside a GIL-released
region, with the object's mutex held, by `_hashlib.HMAC.update()` and
`_hashlib.hmac_new()` when the data exceeds HASHLIB_GIL_MINSIZE bytes.
Setting the exception with the thread state detached crashed the
interpreter instead of raising an exception.
Remove that helper, call the OpenSSL HMAC update function directly in
`_hmac_update()`, and set the exception once the thread state is
re-attached and the mutex is released, as it was done before pythongh-134531.
The OpenSSL error queue is per thread, so the exception type and message
are unaffected.
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Thanks @picnixz for the PR 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖
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picnixz
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Oct 20, 2026
…taching the thread state (GH-159818) (#159926)
gh-159811: Raise OpenSSL errors in `_hashlib.HMAC` after re-attaching the thread state (GH-159818)
`hashlib_openssl_HMAC_update_once()` set an exception when the OpenSSL
HMAC update function failed, but it was called inside a GIL-released
region and the object's mutex held by `_hashlib.HMAC.update()` and
`_hashlib.hmac_new()` when the data exceeds `HASHLIB_GIL_MINSIZE` bytes.
Instead, the HMAC update function is called directly in `_hmac_update()`,
and the exception is set once the thread state is re-attached and the mutex
is released (restores the behavior prior to gh-134531).
Since the OpenSSL error queue is per thread, the exception type and message
are unaffected.
(cherry picked from commit b4b81e1)
Co-authored-by: Bénédikt Tran <[email protected]>
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