Hello,

I would like to report two bugs. I recently upgraded to stunnel 5.50 on FreeBSD 12.0 and noticed that the stunnel server service now crashes periodically. When checking the logs after a crash, I see the following error:

INTERNAL ERROR: Dead canary at /usr/src/crypto/openssl/ssl/statem/extensions_sr

The stunnel server service only ever talks to a stunnel client service, also running version 5.50 on FreeBSD 12.0. The server configuration is as follows. Anything in {} brackets has been redacted. I have seen this issue on multiple servers configured the same way.

<config> client = no setuid = stunnel setgid = stunnel pid = {/path/to/file} output = {/path/to/file} debug = 4 socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1

[server] accept = {ip}:{port} connect = {ip}:{port} ciphers = PSK PSKsecrets = {/path/to/file} </config>

Additionally, I have noticed another error in the logs. Although it appears far more frequently than the error above, it does not seem to cause the server service to crash.

INTERNAL ERROR: Double free attempt: ptr=0x802119050 alloc=/usr/src/crypto/openssl/crypto/stack/stack.c:198 free#1=/usr/src/crypto/openssl/crypto/stack/stack.c:376 free#2=/usr/src/crypto/openssl/ssl/ssl_sess.c:814

Please let me know if additional information is needed to fix these bugs.

Thank you.