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Steve,<br>
<br>
in the two weeks since disabling TLS on the server V2 connection I
haven't had a single crash. While that's not a proof yet the
watchdog issue is TLS related, it's at least a strong indicator.<br>
<br>
The watchdog triggers if the idle task on a core doesn't get a CPU
share for 120 seconds. If the TLS functions block a CPU for more
than a few seconds, that's already pretty bad, as that means TLS
will cause delays in CAN processing (disrupting protocol transfers)
and can possibly cause frame drops and queue overflows. Blocking the
whole system for more than 120 seconds is totally unacceptable.<br>
<br>
This doesn't feel like a calculation / math performance issue, it
rather feels like a bug – and that may imply a security issue
as
well.<br>
<br>
But I don't think this is caused by WolfSSL, as the issue has been
present with mbedTLS as well, just didn't occur that frequently.
Maybe some race condition with the LwIP task?<br>
<br>
Regards,<br>
Michael<br>
<br>
<br>
<div class="moz-cite-prefix">Am 11.04.21 um 09:44 schrieb Michael
Balzer:<br>
</div>
<blockquote type="cite"
cite="mid:7859ecc2-5ea8-4bc6-3da8-a22be88a6661@expeedo.de">Steve,
<br>
<br>
I can confirm an increase of these events since we changed to
WolfSSL, about once every three days currently for me. The
frequency was much lower before, more like once or twice per
month.
<br>
<br>
I've disabled TLS on my module now and will report if that helps.
<br>
<br>
Regards,
<br>
Michael
<br>
<br>
<br>
Am 10.04.21 um 21:20 schrieb Stephen Casner:
<br>
<blockquote type="cite">Michael,
<br>
<br>
As you saw from my earlier emails, I was getting these crashes
<br>
typically after less than 24 hours of operation. I changed my
config
<br>
to disable TLS on server v2 and rebooted 2021-04-05 23:36:04.648
PDT
<br>
and there has not been a crash since. So it definitely appears
to be
<br>
correlated with the additional processing to support TLS.
<br>
<br>
--
Steve
<br>
<br>
On Sun, 4 Apr 2021, Michael Balzer wrote:
<br>
<br>
<blockquote type="cite">Steve,
<br>
<br>
that's the problem with this issue, it's totally unclear what
causes this.
<br>
<br>
The signal dropping begins when the queue is full, which
happens after the
<br>
task has been blocked for ~as many seconds as the queue is
big. So there is no
<br>
logged activity that could cause this, your module basically
went into this
<br>
from idling.
<br>
<br>
Regards,
<br>
Michael
<br>
</blockquote>
<br>
</blockquote>
<br>
<br>
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<pre class="moz-signature" cols="72">--
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