[ntp:questions] ntpdate.c unsafe buffer write
serge.bets at NOSPAM.laposte.invalid
Wed Feb 13 00:56:23 UTC 2008
On Tuesday, February 12, 2008 at 15:04:45 +0000, David L. Mills wrote:
> Serge Bets wrote:
>> ntpd -q can make use of the driftfile to set the kernel frequency
> That was removed as a significant security hazard.
> If you want to rxplicitly set the frequency, use ntptime -f.
Sure: I can preset the frequency by hand. But not setting the frequency
is not a sensible option: it's required for good ntpq -q operations,
otherwise slews don't end on the zero.
> Ths scheme is designed so you can run ntpd until the kernel frequency
> has stabilized, then kill ntpd and run SNTP client at regular
There is no obstacle to that. When ntpd quits, the kernel runs on the
last computed frequency. Without driftfile, ntpd -q runs above this
frequency. With a driftfile, ntpd -q could even run above this frequency
after a reboot.
The obstacle if one existed would be a frequency reset to zero at
startup, like done by loop_config(LOOP_DRIFTINIT). Fortunately this
doesn't happen in mode_ntpdate (the -q flag).
Serge point Bets arobase laposte point net
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