linux-kernel - Re: [PATCH] bridge: fix parsing of MLDv2 reports

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Date:	Fri, 22 May 2015 09:37:17 -0700
From:	Cong Wang <cwang@...pensource.com>
To:	Thadeu Lima de Souza Cascardo <cascardo@...hat.com>
Cc:	Stephen Hemminger <stephen@...workplumber.org>,
	David Miller <davem@...emloft.net>,
	"bridge@...ts.linux-foundation.org" 
	<bridge@...ts.linux-foundation.org>,
	netdev <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Rik.Theys@...t.kuleuven.be
Subject: Re: [PATCH] bridge: fix parsing of MLDv2 reports

On Fri, May 22, 2015 at 8:18 AM, Thadeu Lima de Souza Cascardo
<cascardo@...hat.com> wrote:
> When more than a multicast address is present in a MLDv2 report, all but
> the first address is ignored, because the code breaks out of the loop if
> there has not been an error adding that address.
>
> This has caused failures when two guests connected through the bridge
> tried to communicate using IPv6. Neighbor discoveries would not be
> transmitted to the other guest when both used a link-local address and a
> static address.
>
> This only happens when there is a MLDv2 querier in the network.
>
> The fix will only break out of the loop when there is a failure adding a
> multicast address.
>
> The mdb before the patch:
>
> dev ovirtmgmt port vnet0 grp ff02::1:ff7d:6603 temp
> dev ovirtmgmt port vnet1 grp ff02::1:ff7d:6604 temp
> dev ovirtmgmt port bond0.86 grp ff02::2 temp
>
> After the patch:
>
> dev ovirtmgmt port vnet0 grp ff02::1:ff7d:6603 temp
> dev ovirtmgmt port vnet1 grp ff02::1:ff7d:6604 temp
> dev ovirtmgmt port bond0.86 grp ff02::fb temp
> dev ovirtmgmt port bond0.86 grp ff02::2 temp
> dev ovirtmgmt port bond0.86 grp ff02::d temp
> dev ovirtmgmt port vnet0 grp ff02::1:ff00:76 temp
> dev ovirtmgmt port bond0.86 grp ff02::16 temp
> dev ovirtmgmt port vnet1 grp ff02::1:ff00:77 temp
> dev ovirtmgmt port bond0.86 grp ff02::1:ff00:def temp
> dev ovirtmgmt port bond0.86 grp ff02::1:ffa1:40bf temp
>
> Reported-by: Rik Theys <Rik.Theys@...t.kuleuven.be>
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...hat.com>
> Tested-by: Rik Theys <Rik.Theys@...t.kuleuven.be>


Fixes:  08b202b67264 ("bridge br_multicast: IPv6 MLD support.")

Good catch!
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