gh-145301: Fix double-free in _hashlib module initialization

Author: krylosov-aa

Misc/NEWS.d/next/Library/2026-02-27-19-00-26.gh-issue-145301.2Wih4b.rst

@@ -0,0 +1,3 @@
+Fix a double-free bug in :mod:`_hashlib` module initialization when
+``_Py_hashtable_set()`` fails while adding an algorithm alias to the hash
+table after the primary name was already added

Modules/_hashopenssl.c

@@ -268,7 +268,7 @@ py_hashentry_table_new(void) {
 
         if (h->py_alias != NULL) {
             if (_Py_hashtable_set(ht, (const void*)entry->py_alias, (void*)entry) < 0) {
-                PyMem_Free(entry);
+                /* entry is already in ht, will be freed by _Py_hashtable_destroy() */
                 goto error;
             }
             entry->refcnt++;