Re: [chrony-dev] Patch: avoid infinite select() loop on chronyc

[Cristian Gafton <gafton@xxxxxxxxxx>]

On Mon, 4 Dec 2017, Miroslav Lichvar wrote:

> I suspect the real problem is with the timeout. If it was negative,
> select() would return EINVAL and the loop would not terminate. I guess
> this could happen if chronyd (or something else) stepped the system
> clock forward right between the first gettimeofday() call before the
> request is sent and the second gettimeofday() call before select().
>
> Could that be what happened in your case?

I think you are correct - there was a possibility of some clock step 
happening on the system

> I think the fix should be to check the timeout after its calculation.
> If it is negative, a new attempt should be made.

I still think we need to limit bound the bnmber of attempts. Making the 
assumption tat the next time around on a new attempt things will be 
different is too risky. I'd rather have chronyc exit unsuccessfully than 
keep trying forever the same codepath that already failed once...

Thanks,

--
Cristian


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