The following bits of code call setlogin() before setsid().
Since setlogin affects all processes in the session, this can
change the logname of a different child.

usr.sbin/cron/do_command.c	about line 205

libexec/atrun/atrun.c	fails to call setsid() in become_user().
libexec/uucpd/uucpd.c	fails to call setsid() in doit().
libexec/ftpd/ftpd.c	fails to call setsid() in pass().
libexec/rexecd/rexecd.c	fails to call setsid() in doit().
libexec/rshd/rshd.c	fails to call setsid() in doit().
crypto/dist/heimdal/appl/rsh/rshd.c		in doit()
crypto/dist/heimdal/appl/login/login.c		in doit().

setusercontext() in lib/libutil/login_cap.c calls setlogin() but relies on
the caller to have done a setsid() first...  Only usr.bin/login/login.c
calls setusercontext set LOGIN_SETNAME set.

There may be a problem in gnu/dist/sendmail/sendmail/conf.c
crypto/dist/krb4/appl/bsd/login.c

Since there MAY be a setsid() lurking elsewhere, making the kernel
report if a sessions logname is changed twice could be illiminating.
(the logname is normally inherited then changed).

	David

-- 
David Laight: david@l8s.co.uk