NTP BUG 3067: Fix for bug 2085 broke initial sync calculations
Last update: April 22, 2024 18:49 UTC (7e7bd5857)
Summary
Description
Bug 2085 described a condition where the root delay was included twice, causing the jitter value to be higher than expected. Due to a misinterpretation of a small-print variable in The Book, the fix for this problem was incorrect, resulting in a root distance that did not include the peer dispersion. The calculations and formulae have been reviewed and reconciled, and the code has been updated accordingly.
Mitigation
- Upgrade to 4.2.8p9 or later.
- Properly monitor your
ntpd
instances, and auto-restart ntpd
(without -g
) if it stops running.
Credit
This weakness was discovered independently by Brian Utterback of Oracle, and Sharon Goldberg and Aanchal Malhotra of Boston University.
Timeline