reproduces with pam-1.1.8-1.fc20.x86_64 as well

+++ This bug was initially created as a clone of Bug #1120099 +++

Description of problem:

pam segfaults when user wants to reset his password and a line beginning with his username exists in /etc/security/opasswd, however the record doesn't follow expected structure (e.g. accidentally rewrite content of /etc/security/opasswd with contents of /etc/passwd)

Version-Release number of selected component (if applicable):

pam-1.1.1-17.el6_5.x86_64

How reproducible:

Always

Steps to Reproduce:
1. add remember=3 to /etc/pam.d/system-auth-ac:
# diff /etc/pam.d/system-auth-ac /etc/pam.d/system-auth-ac.bak.2014.07.14
16c16
< password    sufficient    pam_unix.so sha512 shadow nullok try_first_pass use_authtok remember=3
---
> password    sufficient    pam_unix.so sha512 shadow nullok try_first_pass use_authtok

2. # useradd test
3. # passwd test
4. mangle /etc/security/opasswd, e.g.
# cat /etc/security/opasswd
test

or

# cat /etc/security/opasswd
test:x:501:501::/home/test:/bin/bash
5. # su - test
6. $ passwd

Actual results:

Changing password for user test.
Changing password for test.
(current) UNIX password: 
New password: 
Retype new password: 
Segmentation fault

Expected results:

Changing password for user gpedr00.
Changing password for gpedr00.
(current) UNIX password: 
New password: 
Retype new password: 
passwd: Authentication token manipulation error

Additional info:

Patch attached, didn't managed to reproduce the segfault with the patch (doesn't necessarily mean it's bulletproof or elegant). Throwing more descripting error message than just general "passwd: Authentication token manipulation error" would be also fine, not only in this case.