large system date skew on RELENG_6 changes causes select()
failures
Mark Andrews
Mark_Andrews at isc.org
Mon Sep 4 23:41:38 PDT 2006
> Stanislaw Halik wrote this message on Tue, Sep 05, 2006 at 06:51 +0200:
> > Hello,
> >
> > A while ago, by accident, I've changed the system date back to the '98
> > using date(1). To my astonishment, screen(1) barfed about EINVAL in
> > select() and died. Programs, including opera (native FreeBSD-6 binary)
> > kept spinning the CPU until I killed them.
> >
> > I have no means for debugging it.
> >
> > Is this somehow expected? If not (i.e. it's a bug), is it known?
>
> Probably, they calculated timeout's which magicly became negative, which
> isn't a valid timeout, and none of the programs are programmed well enough
> to handle the case and exhibited the behavior that you saw...
Nope. Just a simple limit in itimerfix.
int
itimerfix(struct timeval *tv)
{
if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
tv->tv_usec < 0 || tv->tv_usec >= 1000000)
return (EINVAL);
if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
tv->tv_usec = tick;
return (0);
}
date -j 9809051630 +%s -> 904977000
date +%s -> 1157438219
1157438219 - 904977000 -> 252461219 which is greater that 100000000
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