HMAC.copy() does not correctly copy its attributes

Crash report

What happened?

import hmac
import hashlib

h = hmac.HMAC(b'key', digestmod=hashlib.sha256)
h_copy = h.copy()
print(h_copy.name)

python: ../Modules/_hashopenssl.c:610: const char *get_asn1_utf8name_by_nid(int): Assertion `ERR_peek_last_error() != 0' failed

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Linked PRs

macos works fine

python3.14 works fine

it happens in linux main

errror

Traceback (most recent call last):
  File "/home/yihong/cpython/ttt.py", line 6, in <module>
    print(h_copy.name)
          ^^^^^^^^^^^
  File "/home/yihong/cpython/Lib/hmac.py", line 157, in name
    return self._hmac.name
           ^^^^^^^^^^^^^^^
ValueError: [object identifier routines] unknown nid

seems with openssl problen

yihong@ubuntu:~/cpython$ openssl version
OpenSSL 3.3.1 4 Jun 2024 (Library: OpenSSL 3.3.1 4 Jun 2024)

@picnixz

bisect this commit bring this issue

cc @picnixz

b9c50b4

OK, I know the issue. I forgot to copy the evp_md_nid in hmac.copy so it get initialized to 0, which leads to a crash. Thanks for catching this!

Note: I'm actually surprised that the error indicator is not set in this case, because it goes against OpenSSL docs actually:

OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID n to an ASN1_OBJECT structure, its long name and its short name respectively, or NULL if an error occurred.

So actually we have two issues:

On some OpenSSL versions it seems that OBJ_nid2obj may return NULL without an error indicator set (which is a bit weird though but I guess I can also remove the assertion, it could have been a too strict guard).
The copy is lacking the NID because I forgot to copy the field as well...

So actually we have two issues:

On some OpenSSL versions it seems that OBJ_nid2obj may return NULL without an error indicator set (which is a bit weird though but I guess I can also remove the assertion, it could have been a too strict guard).

The copy is lacking the NID because I forgot to copy the field as well...

yes different OpenSSL version behavior

pythongh-142451: correctly copy HMAC attributes in `HMAC.copy()`

gh-142451: correctly copy HMAC attributes in `HMAC.copy()` (#142510)

Thank you for the report!

I'm going to re-use this issue for the lack of block_size in HMAC.copy as well.

pythongh-142451: correctly copy `HMAC.block_size` attribute

[3.14] gh-142451: correctly copy HMAC attributes in `HMAC.copy()` (GH…

[3.13] gh-142451: correctly copy HMAC attributes in `HMAC.copy()` (GH…

pythongh-142451: correctly copy HMAC attributes in `HMAC.copy()` (pyt…

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HMAC.copy() does not correctly copy its attributes #142451

Crash report

What happened?

CPython versions tested on:

Operating systems tested on:

Output from running 'python -VV' on the command line:

Linked PRs

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HMAC.copy() does not correctly copy its attributes #142451

Description

Crash report

What happened?

CPython versions tested on:

Operating systems tested on:

Output from running 'python -VV' on the command line:

Linked PRs

Activity

yihong0618 commented on Dec 9, 2025

yihong0618 commented on Dec 9, 2025

picnixz commented on Dec 9, 2025

picnixz commented on Dec 9, 2025

yihong0618 commented on Dec 10, 2025

picnixz commented on Dec 14, 2025

picnixz commented on Dec 14, 2025

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