From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Wed, 03 Apr 2013 10:58:37 -0700
From: Andy Lutomirski <luto@amacapital.net>
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To: Eric Dumazet <eric.dumazet@gmail.com>
CC: Sven Joachim <svenjoac@gmx.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	Ding Tianhong <dingtianhong@huawei.com>,
	Eric Dumazet <edumazet@google.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [ 105/124] af_unix: dont send SCM_CREDENTIAL when dest socket
 is NULL
References: <20130402221104.163133110@linuxfoundation.org>  <20130402221116.307254752@linuxfoundation.org>  <87vc833kpf.fsf@turtle.gmx.de> <1364997630.13853.19.camel@edumazet-glaptop>  <87a9pfzm33.fsf@turtle.gmx.de> <1365003300.13853.25.camel@edumazet-glaptop>
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On 04/03/2013 08:35 AM, Eric Dumazet wrote:
> On Wed, 2013-04-03 at 17:10 +0200, Sven Joachim wrote:
>> On 2013-04-03 16:00 +0200, Eric Dumazet wrote:
> 
>>
>>> It might be a wrong sender (application bug or bad identity), and udevd
>>> correctly discards the incoming message.
>>
>> How would I find out the culprit?
> 
> Change udevd to display the pid as well, and hopefully track the sender.
> 
> udevd receives uid and pid in the credentials.

This sounds suspiciously like an SCM_CREDENTIALS bug triggered by a
race.  There's a fix (that needs both a new version from me and a review
by someone) here:

http://www.spinics.net/lists/netdev/msg229948.html

--Andy