I switch to md5-hashing by replacing \"prefix=$2a$\" in /etc/pam.d/system-auth with \"md5\", create a new user and try to set a password for him. passwd (run under root) fails to do this:

Enter new password: 
Re-type new password: 
passwd: Memory buffer error.

(And with  \"prefix=$2a$\" it works.)

In syslog-messages we can see this:
Jul  4 20:37:28 shamrock pam_tcb[18898]: crypt_gensalt_ra: Invalid argument

---
use the attached /etc/pam.d/system-auth

$ useradd t
$ passwd t

You can now choose the new password or passphrase.

A valid password should be a mix of upper and lower case letters,
digits and other characters.  You can use an 8 character long
password with characters from at least 3 of these 4 classes, or
a 7 character long password containing characters from all the
classes.  Characters that form a common pattern are discarded by
the check.

A passphrase should be of at least 3 words, 12 to 40 characters
long and contain enough different characters.

Alternatively, if noone else can see your terminal now, you can
pick this as your password: \"format_behave&exempt\".

Enter new password: 
Re-type new password: 
passwd: Memory buffer error.
$ 

---
# rpm -qa passwd \'*tcb*\' \'*pam*\' glibc | sort -u               
glibc-2.2.5-alt10
libpam-0.75-alt15
libtcb-0.9.7.1-alt1
nss_tcb-0.9.7.1-alt1
pam-0.75-alt15
pam-config-1.1.2-alt1
pam_console-0.75-alt15
pam_passwdqc-0.4-alt3
pam_tcb-0.9.7.1-alt1
pam_userpass-0.5-alt3
passwd-1.0.0-alt1
tcb-utils-0.9.7.1-alt1# rpm -qa passwd \'*tcb*\' \'*pam*\' glibc | sort -u | xargs rpm -V
S.5....T c /etc/pam.d/system-auth