[stunnel-users] Memory Leak in stunnel 5.31

Thu Mar 31 22:28:56 CEST 2016

Hello,

we have a memory leak with stunnel 5.31 in server mode on Windows Server
2012. Page File Bytes of the stunnel process keep growing. The more
traffic the faster it's growing, until memory is exhausted and client
connects start to fail with:

2016.03.31 15:50:30 LOG3[main]: _beginthread: Exec format error (8)
2016.03.31 15:50:30 LOG3[main]: Connection rejected: create_client failed

I suspect it has something to do with clients not closing the connection
correctly. We have a lot of connections ending like this:

2016.03.31 09:21:48 LOG3[5156]: SSL_shutdown: Connection reset by peer
(WSAECONNRESET) (10054)
2016.03.31 09:21:48 LOG5[5156]: Connection reset: 239 byte(s) sent to
SSL, 722 byte(s) sent to socket

Is my suspicion plausible? Can you recommend a change in the
configuration to avoid this issue? Anything else I can do to debug?

The config looks something like this:

cert = C:\crt.pem
key = C:\key.key
ciphers = ALL:!DH:!aNULL:!eNULL:!LOW:!EXP
socket = l:TCP_NODELAY=1
socket = r:TCP_NODELAY=1
verify = 2
CAfile = C:\All-In-One.pem

[test]
accept = 23456
connect = 10.10.10.10