Hello Markus,
I tried to fill in the symbol information that were missing
in the above backtrace by using the available dbgsym
packages python3-cryptography-dbgsym and libssl1.1-dbgsym.
With these installed your gdb would show line information too [3].
I found following ticket [2] that shows in later entries
similarities to the given backtrace.
Further running the server with valgrind might show something
related, if the crash happens there too.
Kind regards,
Bernhard
[1]
...
#4 0x...42c in _int_free at malloc.c:4165
#5 0x...9be in SSL_SESSION_free at ../ssl/ssl_sess.c:765
#6 0x...c8c in doall_util_fn at ../crypto/lhash/lhash.c:196
#7 0x...f57 in lh_SSL_SESSION_doall_TIMEOUT_PARAM at ../ssl/ssl_sess.c:1082
#8 0x...4d3 in tls_finish_handshake at ../ssl/statem/statem_lib.c:1075
#9 0x...e3e in state_machine / write_state_machine at
../ssl/statem/statem.c:810
#10 0x...f34 in SSL_do_handshake at ../ssl/ssl_lib.c:3607
#11 0x...71c in _cffi_f_SSL_do_handshake at
build/temp.linux-amd64-3.7/_openssl.c:38289
...
[2] https://twistedmatrix.com/trac/ticket/9764
[3] https://wiki.debian.org/HowToGetABacktrace
