Indefinite hang in getaddrinfo / check_pf / make_request

Steven Schlansker
Tue Sep 29 22:05:00 GMT 2015

On Sep 24, 2015, at 11:36 AM, Steven Schlansker <> wrote:

> On Sep 22, 2015, at 9:59 PM, Steven Schlansker <> wrote:
>>> On Sep 22, 2015, at 9:04 PM, Paul Pluzhnikov <> wrote:
>>> On Tue, Sep 22, 2015 at 8:53 PM, Steven Schlansker
>>> <> wrote:
>>>> We found the following issue:
>>> You may be seeing instead.
>>> See if that patch has been applied to your sources as well.
>> Thanks for finding this.  While that fix is not applied to our deployed version,
>> I think the symptoms are slightly different
> Thanks Paul and Adhemerval for the advice.  I believe I have evidence that this is
> not the same issue as either 15946 or 12926.

> ...
> I am going to spend some time trying to distill down a test case that just exercises the check_pf code and see if I can reproduce in isolation.
> In the meantime, does anyone have any ideas for further diagnostics that would be useful?  I'm not sure how to check the kernel side of the netlink socket effectively,
> to see if it actually tried to reply or not...

Hello again, in case anyone stumbles across this in the future --
I got a test case, and narrowed it down further.  It seems to be related
to incorrect kernel handling of the netlink sockets; under contention
they can get lost:

Kernel 4.0.4 is known to be affected.  We're testing out 4.0.9
in the hopes it is not.  So this is in fact a new bug, albeit
not a glibc bug.

Thank you for your time.

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