Description of problem:

There's a dracut module for reencryption of rootfs device from initrd phase. This module runs following command (one particular example that's able to hit the issue):

/bin/plymouth ask-for-password --prompt "some message" --command="/sbin/cryptsetup-reencrypt /dev/sda2 -T 1 --use-fsync --progress-frequency 5 -B 32"

Sometimes (it's not 100% reproducible) this command ends in endless loop due to following:

a) user inputs passphrase in plymouth prompt (non empty string only input)
b) cryptsetup-reencrypt process starts and get STDIN filedescriptor set to EOF (iow read() syscall on stdin returns 0 immediately)
c) cryptsetup-reencrypt fails with error (Nothing to read)
d) it's immediately restarted and here we're moving to step b) again.

b) to d) repeats endlessly.

Note that it's not 'plymouth' command that is repeated. The plymouth command runs cryptsetup-reencrypt in endless loop with broken stdin.

Version-Release number of selected component (if applicable):
kernel-3.10.0-919.el7.x86_64
plymouth-0.8.9-0.31.20140113.el7.x86_64
dracut-033-547.el7.x86_64

cryptsetup-2.0.3-1.el7
cryptsetup-1.7.4-4.el7 (it doesn't matter which cryptsetup version. Tested with 7.5 version and with rebased 2.0.3 for RHEL7.6)

How reproducible:
Not always, testing on VM in qemu.

Actual results:
Occasional endless loop.

Expected results:
Passphrase is passed correctly to STDIN of --command.

Additional info:
It seems to be easier to reproduce when I route serial to host via "console=ttyS0,115200 console=tty" kernel cmdline parameters.