Re: [chrony-dev] crash when overloading refclock_sock

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Did you really have 23 samples come at the same time to a nanosec? I have no
idea how that is evan possible. Or did you artificially swamp the refclock
shm?


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On Fri, 7 Oct 2016, Nuno Gonçalves wrote:

Hi,

Still crashes:

2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
63 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
0 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
1 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
2 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
3 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
4 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
5 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
6 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
7 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
8 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
9 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
10 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
11 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
12 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
13 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
14 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
15 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
16 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
17 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
18 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
19 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z refclock.c:713:(filter_add_sample) filter sample
20 t=1475822340.876999761 offset=0.123000145 dispersion=0.000000001
2016-10-07T06:39:01Z sources.c:360:(SRC_AccumulateSample) ip=[SOCK]
t=1475822340.876999761 ofs=-0.123000 del=0.000000 disp=-nan str=0
2016-10-07T06:39:01Z sourcestats.c:550:(SST_DoNewRegression) off=-nan
freq=-nan skew=-nan n=3 bs=0 runs=3 asym=0.000000 arun=0
chronyd: sourcestats.c:388: find_best_sample_index: Assertion
`best_index >= 0' failed.
Aborted (core dumped)

Thanks,
Nuno

On Thu, Oct 6, 2016 at 4:20 PM, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
On Wed, Oct 05, 2016 at 10:56:04AM +0200, Nuno Gonçalves wrote:
I was testing a refclock_sock provider and when the rate of messages
is really high (over 50k/s), I manage to crash chronyd.

Yes, this is not the standard use case, usually I publish 1/s, but
anyway chrony ideally should resist to this abuse.


2016-10-05T07:58:01Z refclock.c:707:(filter_add_sample) filter sample
52 t=1475654280.876999978 offset=0.122999928 dispersion=0.000000001
2016-10-05T07:58:01Z refclock.c:707:(filter_add_sample) filter sample
53 t=1475654280.876999978 offset=0.122999928 dispersion=0.000000001
2016-10-05T07:58:01Z refclock.c:707:(filter_add_sample) filter sample
54 t=1475654280.876999978 offset=0.122999928 dispersion=0.000000001
2016-10-05T07:58:01Z refclock.c:707:(filter_add_sample) filter sample
55 t=1475654280.876999978 offset=0.122999928 dispersion=0.000000001
2016-10-05T07:58:01Z sources.c:360:(SRC_AccumulateSample) ip=[SOCK]
t=1475654280.876999978 ofs=-0.123000 del=0.000000 disp=-nan str=0
chronyd: sourcestats.c:388: find_best_sample_index: Assertion
`best_index >= 0' failed.
Aborted (core dumped)

Thanks for the bug report. It looks like the problem is that there are
multiple samples with the same local timestamp, which breaks the
calculation of the dispersion.

Can you please pull from git and see if it's fixed?

--
Miroslav Lichvar

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