Is there anything usefull beside breaking my cronjobs? I
can't do a su (in my case a su to an account with uid 0
and a shellscript as loginshell, nothing dangerous on this
machine because there are no accounts besides mine, but
very important for putting new dhcpd.conf's in place and
restarting my dhcpd). This is new to rh-6.0 as
"strings /bin/su | grep tty" on my 5.x boxes told me.

root@rfhpc0014:/usr/src/redhat/SOURCES # more
sh-utils-1.16-nostdin.patch
--- sh-utils-1.16/src/su.c.nostdin      Thu Apr  1 10:26:02
1999
+++ sh-utils-1.16/src/su.c      Thu Apr  1 10:32:12 1999
@@ -376,7 +376,6 @@
 correct_password (const struct passwd *pw)
 {
 #ifdef USE_PAM
-
   /* root always succeeds; this isn't an authentication
question (no
    * extra privs are being granted) so it shouldn't
authenticate with PAM.
    * However, we want to create the pam_handle so that
proper credentials
@@ -385,6 +384,13 @@
   PAM_BAIL_P;
   if (getuid () == 0)
     return 1;
+
+  if (!isatty(0)) {
+       fprintf(stderr, "standard in must be a tty\n");
+       exit(1);
+  }
+
+
   retval = pam_authenticate(pamh, 0);
   PAM_BAIL_P;
   retval = pam_acct_mgmt(pamh, 0);