untrusted comment: signature from openbsd 6.1 base secret key
RWQEQa33SgQSEml3TkqBRg680RBxu/ZjYLuIcw4QfG1sCxlmtYdq78vDWDLrOKVepw5RgmvBQIsQIPex5Hx9HNRQHzjAh8ZtNgs=

OpenBSD 6.1 errata 019, August 3, 2017:

With an invalid address family, tcp_usrreq() may take an unintended code path.

Apply by doing:
   signify -Vep /etc/signify/openbsd-61-base.pub -x 019_tcp_usrreq.patch.sig \
       -m - | (cd /usr/src && patch -p0)

And then rebuild and install a new kernel:
   KK=`sysctl -n kern.osversion | cut -d# -f1`
   cd /usr/src/sys/arch/`machine`/compile/$KK
   make obj
   make config
   make
   make install

Index: sys/netinet/tcp_usrreq.c
===================================================================
RCS file: /cvs/src/sys/netinet/tcp_usrreq.c,v
--- sys/netinet/tcp_usrreq.c    20 Jul 2016 19:57:53 -0000      1.134
+++ sys/netinet/tcp_usrreq.c    2 Aug 2017 16:37:39 -0000
@@ -236,9 +236,9 @@ tcp_usrreq(so, req, m, nam, control, p)
                       }

                       error = in6_pcbconnect(inp, nam);
-               } else if (sin->sin_family == AF_INET)
+               } else
#endif /* INET6 */
-               {
+               if (sin->sin_family == AF_INET) {
                       if ((sin->sin_addr.s_addr == INADDR_ANY) ||
                           (sin->sin_addr.s_addr == INADDR_BROADCAST) ||
                           IN_MULTICAST(sin->sin_addr.s_addr) ||
@@ -248,6 +248,8 @@ tcp_usrreq(so, req, m, nam, control, p)
                       }

                       error = in_pcbconnect(inp, nam);
+               } else {
+                       error = EAFNOSUPPORT;
               }

               if (error)