Here is how you can create the problem.
Make a copy of your "fstab" corrupt the "fstab" to simulate a failed disk and 
reboot.
It drops you to the maintenance prompt and asks you for a password - at this 
point you are done.
The only rescue scheme we have found is to reinstall the system, recreate the 
disk partitions,  - failed disk, do not format partitions and after it writes 
a new "fstab", bail out - power off and restart.   System come up minus 
failed disk and everything works.
Discovered this early late Sunday evening after a disk failure and major power 
failure to facility at the same time.
Rude and Crude but it works.

Larry Linder

On Thursday 02 February 2012 5:19 pm, Yasha Karant wrote:
> I have been discussing the failure mode that I have observed:
>
> also documented in
>
> https://bugzilla.redhat.com/show_bug.cgi?id=636628
>
> after fsck fails during a (re)boot
>
> Give root password for maintenance
> (or type Control-D to continue):
>
> At this stage, at every second key stroke, it reports "Login incorrect."
> and repeats the above "Give root password...".
>
> as an endless loop.
>
> The argument has been presented on this list that it is the root user
> failure to configure a password into grub.conf or other bootloading or
> initialization applications/routines configuration or input data files.
>
> I have been discussing this issue with a number of experienced systems
> persons, and none of us accept this argument, especially as without
> special intervention or configuration, the expected behavior was
> displayed on EL 4 and 5, as well as several other non-TUV distributions.
>   Expected behavior:  whatever root password was encoded into the
> /etc/shadow file is used by the routine that handles "Give root password
> for maintenance" is accepted, and not at every second key stroke would
> it report "Login incorrect."
>
> When the system is first installed from physical media such as a
> bootable DVD (for EL, this is with every major release, e.g., EL 4, EL
> 5, EL 6, etc.), and a root password is required to be set during
> installation, this password is put in an encrypted form in the
> appropriate file in /etc (e.g., /etc/shadow) and wherever else it might
> be required (e.g., in /boot if the particular implementation were to
> require this).  Moreover, for fsck to run during the boot process, even
> if /boot is on a separate partition from / (root partition), the fsck
> executable is on a partition that must have been mounted, and thus
> /etc/shadow should be available.  Hence, the (encrypted) password should
> be available.
>
> The bug is that the password entry routine (as in response to the prompt
> "Give root password for maintenance") does not accept the full vector of
> characters for the root password including the Enter keystroke that
> terminates the vector.
>
> As there are correspondents to this list that evidently feel the above
> arguments to be incorrect, references to the relevant Linux source code
> sections and design documents (e.g., state machine chart for the
> sequence that contains "Give root password for maintenance") greatly
> would be appreciated.
>
> Yasha Karant