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Description of problem:
pam_fail_delay() function documentation states that it will delay execution by given time +- 25%, but it actually waits for given time +- 50%

Version-Release number of selected component (if applicable):
pam-1.1.1-17.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. set pam_fail_delay()
2. measure time of failed pam_authenticate()

Actual results:
When delay was set to 20s, I got this distribution:
      3 11s
     20 12s
     24 13s
     51 14s
    140 15s
    197 16s
    190 17s
    166 18s
    197 19s
    296 20s
    417 21s
    445 22s
    350 23s
    208 24s
     93 25s
     59 26s
     51 27s
     41 28s
     10 29s
      1 30s

Expected results:
Either the times to be between 15 and 25 seconds, or adjust documentation accordingly.

Additional info:
I already reported an upstrem bug after consulting with tmraz - https://fedorahosted.org/linux-pam/ticket/36

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-0901.html