Re: wslog, windows, pytest, and heap corruption

[Gerald Combs <gerald () wireshark org>]

On 12/29/21 5:15 PM, John Thacker wrote:
> I was working on a MR for moving the text2pcap/text_import debug over to the ws_log features and I ran into a seemingly 
> bizarre problem. Setting the log level to a non-default value causes the pytest procedures to fail with heap corruption 
> on the Gitlab Windows CI.
>
> Some of the text2pcap pytests depend on grepping through the stderr output for some of the debug information. Those tests originally passed the -d 
> flag to text2pcap, so I replaced it with setting the log level to "debug" (and later "info") with the standard "--log-level 
> debug" argument read by ws_log_parse_args().
>
> On Windows (but not Linux or MacOS, not clang or gcc, nor with either using ASAN), those tests which set the log level 
> (and only those tests) started failing with a return code of 0xc0000374, heap corruption.
>
> As I looked into it closer, all the debug information that those tests used ought to be logged at "warning" or 
> "message," which are at the default log level, so I was able to remove that flag, and then it passed.
>
> It looks like it might be related to some of the things discussed here, though I'm not 100% sure because I'm not a 
> Windows programmer:
>
> https://discuss.wxpython.org/t/heap-corruption-on-windows/35583 
> <https://discuss.wxpython.org/t/heap-corruption-on-windows/35583>
> https://bugs.python.org/issue36792 <https://bugs.python.org/issue36792>
> https://bugs.python.org/issue37945 <https://bugs.python.org/issue37945>
>
> There's some kind of issue seen in Python 3.8 and higher, with Windows 10 build 1809 (which is a long term support 
> build that is what the CI build server uses), with UTF-8 locales, with log systems that get system locale information and 
> print dates, the Windows 10 Universal CRT, and heap corruption.
>
> It might have something to do with the tests spawning a lot of subprocesses in parallel and setting the log level to a 
> different value eventually calling free_log_filter() from ws_log_set_debug_filter().
>
> John Thacker

Is https://gitlab.com/wireshark/wireshark/-/pipelines/438735249 one of the pipelines that failed? If so, it looks like 
Wireshark is crashing and Python is complaining about its return code:

----
Traceback (most recent call last):
  File "C:\builds\wireshark\wireshark\test\fixtures.py", line 54, in wrapped
    test_fn(self, *fixtures)
  File "C:\builds\wireshark\wireshark\test\suite_text2pcap.py", line 186, in test_text2pcap_ikev1_certs_pcap
    check_text2pcap(self, 'ikev1-certs.pcap', 'pcap')
  File "C:\builds\wireshark\wireshark\test\suite_text2pcap.py", line 144, in check_text2pcap_real
    self.assertRun(text2pcap_cmd, shell=True)
  File "C:\builds\wireshark\wireshark\test\subprocesstest.py", line 304, in assertRun
    self.assertEqual(process.returncode, expected_return)
AssertionError: 3221226356 != 0
----

Just a wild guess, but maybe we need to call setlocale at the beginning of text2pcap similar to our other executables?
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