netdev - Re: [PATCH net] ipv6: replacing a rt6_info needs to purge possible propagated rt6

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Message-ID: <1422288516.2687.27.camel@stressinduktion.org>
Date:	Mon, 26 Jan 2015 17:08:36 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org, lkundrak@...sk
Subject: Re: [PATCH net] ipv6: replacing a rt6_info needs to purge possible
 propagated rt6_infos too

On Mo, 2015-01-26 at 08:02 -0800, Eric Dumazet wrote:
> On Mon, 2015-01-26 at 15:11 +0100, Hannes Frederic Sowa wrote:
> > Lubomir Rintel reported that during replacing a route the interface
> > reference counter isn't correctly decremented.
> > 
> > To quote bug <https://bugzilla.kernel.org/show_bug.cgi?id=91941>:
> > | [root@...l7-5 lkundrak]# sh -x lal
> > | + ip link add dev0 type dummy
> > | + ip link set dev0 up
> > | + ip link add dev1 type dummy
> > | + ip link set dev1 up
> > | + ip addr add 2001:db8:8086::2/64 dev dev0
> > | + ip route add 2001:db8:8086::/48 dev dev0 proto static metric 20
> > | + ip route add 2001:db8:8088::/48 dev dev1 proto static metric 10
> > | + ip route replace 2001:db8:8086::/48 dev dev1 proto static metric 20
> > | + ip link del dev0 type dummy
> > | Message from syslogd@...l7-5 at Jan 23 10:54:41 ...
> > |  kernel:unregister_netdevice: waiting for dev0 to become free. Usage count = 2
> > |
> > | Message from syslogd@...l7-5 at Jan 23 10:54:51 ...
> > |  kernel:unregister_netdevice: waiting for dev0 to become free. Usage count = 2
> > 
> > During replacement of a rt6_info we must walk all parent nodes and check
> > if the to be replaced rt6_info got propagated. If so, replace it with
> > an alive one.
> > 
> > Reported-by: Lubomir Rintel <lkundrak@...sk>
> > Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> 
> Hi Hannes
> 
> Was this bug added in commit 4a287eba2de395713d8b2b2aeaa69fa086832d34
> ("IPv6 routing, NLM_F_* flag support: REPLACE and EXCL flags support,
> warn about missing CREATE flag") ?

Yes, this patch added the hunk which introduced this problem. Sorry, I
didn't bother to look into git history which patch was responsible,
because I thought it might well be there from the beginning of the
stack.

Fixes: 4a287eba2de3957 ("IPv6 routing, NLM_F_* flag support: REPLACE and EXCL flags support, warn about missing CREATE flag")


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