In HEAD when using sudo_setenv() to set KRB5CCNAME sudo is segfaulting and is reproducible on FreeBSD and Linux.  The bactrace I received simply indicated a crash in strncmp(). The offending code is in env.c's insert_env():

    if (dupcheck) {
	    varlen = (strchr(str, '=') - str) + 1;

	    for (nep = env.envp; *nep; nep++) {
==>		if (strncmp(str, *nep, varlen) == 0) {
		    *nep = str;
		    return;
		}
	    }

After adding a printf() to figure out which environmental variable is causing this I get the following:

[tom@releng-7-fbsd sudo-devel]$ sudo -l                
LDAP Config Summary
===================
uri              ldap://shorthair.straycat.dhs.org
ldap_version     3
sudoers_base     ou=Sudoers,dc=straycat,dc=dhs,dc=org
binddn           (anonymous)
bindpw           (anonymous)
bind_timelimit   -1
timelimit        -1
ssl              start_tls
use_sasl         1
sasl_auth_id     (NONE)
rootuse_sasl     -1
rootsasl_auth_id (NONE)
sasl_secprops    (NONE)
krb5_ccname      /usr/local/etc/.ldapcache
===================
ldap_set_option(LDAP_OPT_X_TLS_CACERTFILE, "/etc/ssl/straycat.crt")
sudo: ldap_initialize(ld,ldap://shorthair.straycat.dhs.org)
ldap_set_option(LDAP_OPT_PROTOCOL_VERSION, 3)
sudo: ldap_start_tls_s() ok
*nep = bfbfecfc (_=/usr/local/bin/sudo)
*nep = bfbfed12 (SSH_CONNECTION=192.168.1.127 59783 192.168.1.73 22)
*nep = bfbfed45 (PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/games:/usr/ports/Tools/scripts)
*nep = bfbfedab (SHELL=/usr/local/bin/ksh)
*nep = bfbfedc4 (EDITOR=vim)
*nep = bfbfedcf (BLOCKSIZE=K)
Segmentation fault (core dumped)

[tom@releng-7-fbsd sudo-devel]$ env
_=/usr/bin/env
SSH_CONNECTION=192.168.1.127 59783 192.168.1.73 22
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/games:/usr/ports/Tools/scripts
SHELL=/usr/local/bin/ksh
EDITOR=vim
BLOCKSIZE=K
JAILED=1
USER=tom
SSH_CLIENT=192.168.1.127 59783 22
JAILMJVER=7
TERM=xterm
PACKAGESITE=http://ftp.straycat.dhs.org/tb/packages/7-i386-FreeBSD/Latest/
FTP_PASSIVE_MODE=YES
__MAKE_CONF=/home/tom/src/etc/make.conf
LOGNAME=tom
KRB5CCNAME=FILE:/tmp/krb5cc_sCQKJt
SSH_TTY=/dev/ttyp0
ENV=/home/tom/.kshrc
CVSEDITOR=vim
JAILNAME=fbsd
MAIL=/var/mail/tom
DISPLAY=bofh:0
HOME=/home/tom
PWD=/home/tom/src/FREEBSD/ports/security/sudo-devel
PAGER=more
CDIFFCOLORS=93:91:96:41:1:1;31


On my Linux box I see a slightly different result though:

*nep = bfccdba5 (HOSTNAME=centos.straycat.dhs.org)
*nep = bfccdbc6 (SHELL=/bin/bash)
*nep = bfccdbd6 (TERM=vt220)
*nep = bfccdbe1 (HISTSIZE=500)
*nep = bfccdbee (SSH_CLIENT=192.168.1.127 55090 22)
*nep = bfccdc10 (SSH_TTY=/dev/pts/1)
Segmentation fault

HOSTNAME=centos.straycat.dhs.org
SHELL=/bin/bash
TERM=vt220
HISTSIZE=500
SSH_CLIENT=192.168.1.127 55090 22
SSH_TTY=/dev/pts/1
USER=tom
LS_COLORS=no=00:fi=00:di=00;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz=00;31:*.arj=00;31:*.taz=00;31:*.lzh=00;31:*.zip=00;31:*.z=00;31:*.Z=00;31:*.gz=00;31:*.bz2=00;31:*.bz=00;31:*.tz=00;31:*.rpm=00;31:*.cpio=00;31:*.jpg=00;35:*.gif=00;35:*.bmp=00;35:*.xbm=00;35:*.xpm=00;35:*.png=00;35:*.tif=00;35:
CDIFFCOLORS=93:91:96:41:1:1;31
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/X11R6/bin:/usr/X11R6/sbin:/usr/kerberos/sbin:/usr/kerberos/bin
MAIL=/var/spool/mail/tom
PWD=/home/tom/src/sudo-1.7
INPUTRC=/etc/inputrc
EDITOR=vim
LANG=en_US.UTF-8
KRB5CCNAME=FILE:/tmp/krb5cc_10001_mReEr19811
HOME=/home/tom
SHLVL=1
LOGNAME=tom
SSH_CONNECTION=192.168.1.127 55090 192.168.1.51 22
LESSOPEN=|/usr/bin/lesspipe.sh %s
CVSEDITOR=vim
G_BROKEN_FILENAMES=1
_=/bin/env
OLDPWD=/home/tom