Crash using QSslCertificate.subjectAlternateNames?

[Jeremy Katz]

Hi,

I'm seeing a crash calling QSslCertificate.subjectAlternateNames(). It 
takes a few calls to fail, but seems to be consistent for a 
client:server pair.

Software versions:
macOS 12 or Fedora 32 and 35, Ubuntu 20.04?
PyQt 5.15.[4,5,6]
Qt 5.15.[2,5,7]
Python 3.[7,10]

I've been told that it doesn't occur with PyQt and Qt 5.12.

The Linux stack trace suggests the issue is in PyQt's conversion of the 
returned QMultiMap:

#0  _PyObject_GC_UNTRACK
#1  PyObject_GC_UnTrack
#2  subtype_dealloc
#3  convertFrom_QMultiMap_0100QSsl_AlternativeNameEntryType_0100QString
#4  sip_api_convert_from_new_type
#5  meth_QSslCertificate_subjectAlternativeNames
...

The Mac stack trace isn't as obvious to me:

* thread #2, queue = 'com.apple.main-thread', stop reason = 
EXC_BAD_ACCESS (code=1, address=0xaa)
   * frame #0: Python`_PyType_Lookup + 42
     frame #1: Python`_PyObject_LookupSpecial + 40
     frame #2: Python`PyObject_Format + 117
     frame #3: Python`output_markup + 1176
     frame #4: Python`build_string + 393
     frame #5: Python`do_string_format + 97
     frame #6: Python`_PyMethodDef_RawFastCallKeywords + 685
     frame #7: Python`_PyMethodDescr_FastCallKeywords + 82
     frame #8: Python`call_function + 780
     frame #9: Python`_PyEval_EvalFrameDefault + 25155
     frame #10: Python`function_code_fastcall + 128
     frame #11: Python`_PyFunction_FastCallDict + 148
     frame #12: QtCore.abi3.so`PyQtSlot::call(_object*, _object*) const + 39
     frame #13: QtCore.abi3.so`PyQtSlot::invoke(void**, _object*, void*, 
bool) const + 374

=== Test program ===

import sys

import PyQt5.QtCore as QtCore
import PyQt5.QtNetwork as QtNetwork

def handleFinished(reply):
     while True:
         for cert in reply.sslConfiguration().peerCertificateChain():
             for k,v in cert.subjectAlternativeNames().items():
                 print("{}, {}".format(k, v))

app = QtCore.QCoreApplication(sys.argv)
url = QtCore.QUrl(sys.argv[1])
qnam = QtNetwork.QNetworkAccessManager()
qnam.setAutoDeleteReplies(True)
qnam.finished.connect(handleFinished)
request = QtNetwork.QNetworkRequest(url)
qnam.get(request)

app.exec()

=== Example output ===
$ python3 ~/vm_shared/tmp/subjectaltnames.test.py https://www.google.com
1, ['www.google.com']
1, ['www.google.com']
1, ['www.google.com']
Abort trap: 6
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