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Subject: Re: [PATCH 4.19 01/24] bridge: do not add port to router list when
 receives query with source 0.0.0.0
From:   Sebastian Gottschall <s.gottschall@newmedia-net.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Ying Xu <yinxu@redhat.com>, Hangbin Liu <liuhangbin@gmail.com>,
        Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
        Roopa Prabhu <roopa@cumulusnetworks.com>,
        "David S. Miller" <davem@davemloft.net>
References: <20181102182839.725385066@linuxfoundation.org>
 <20181102182839.913422845@linuxfoundation.org>
 <07d315a2-d735-3d8b-686c-9c52acf91bf1@newmedia-net.de>
 <20190217164809.GA24091@kroah.com>
 <7978727a-eacc-779c-771f-f4c3013237f3@newmedia-net.de>
Message-ID: <0425449f-f6d9-c492-d7c8-ba202db88d26@newmedia-net.de>
Date:   Wed, 20 Feb 2019 13:48:47 +0100
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*reminder*

Am 18.02.2019 um 11:18 schrieb Sebastian Gottschall:
>
> Am 17.02.2019 um 17:48 schrieb Greg Kroah-Hartman:
>> On Sun, Feb 17, 2019 at 03:29:22PM +0100, Sebastian Gottschall wrote:
>>> according to user reports this patch will cause a serious 
>>> regression. igmp
>>> snooping is not working anymore with this patch
>>>
>>> Am 02.11.2018 um 19:34 schrieb Greg Kroah-Hartman:
>>>> 4.19-stable review patch.  If anyone has any objections, please let 
>>>> me know.
>>>>
>>>> ------------------
>>>>
>>>> From: Hangbin Liu <liuhangbin@gmail.com>
>>>>
>>>> [ Upstream commit 5a2de63fd1a59c30c02526d427bc014b98adf508 ]
>>>>
>>>> Based on RFC 4541, 2.1.1.  IGMP Forwarding Rules
>>>>
>>>>     The switch supporting IGMP snooping must maintain a list of
>>>>     multicast routers and the ports on which they are attached.  This
>>>>     list can be constructed in any combination of the following ways:
>>>>
>>>>     a) This list should be built by the snooping switch sending
>>>>        Multicast Router Solicitation messages as described in IGMP
>>>>        Multicast Router Discovery [MRDISC].  It may also snoop
>>>>        Multicast Router Advertisement messages sent by and to other
>>>>        nodes.
>>>>
>>>>     b) The arrival port for IGMP Queries (sent by multicast routers)
>>>>        where the source address is not 0.0.0.0.
>>>>
>>>> We should not add the port to router list when receives query with 
>>>> source
>>>> 0.0.0.0.
>>>>
>>>> Reported-by: Ying Xu <yinxu@redhat.com>
>>>> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
>>>> Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
>>>> Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
>>>> Signed-off-by: David S. Miller <davem@davemloft.net>
>>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>>> ---
>>>>    net/bridge/br_multicast.c |   10 +++++++++-
>>>>    1 file changed, 9 insertions(+), 1 deletion(-)
>>>>
>>>> --- a/net/bridge/br_multicast.c
>>>> +++ b/net/bridge/br_multicast.c
>>>> @@ -1420,7 +1420,15 @@ static void br_multicast_query_received(
>>>>            return;
>>>>        br_multicast_update_query_timer(br, query, max_delay);
>>>> -    br_multicast_mark_router(br, port);
>>>> +
>>>> +    /* Based on RFC4541, section 2.1.1 IGMP Forwarding Rules,
>>>> +     * the arrival port for IGMP Queries where the source address
>>>> +     * is 0.0.0.0 should not be added to router port list.
>>>> +     */
>>>> +    if ((saddr->proto == htons(ETH_P_IP) && saddr->u.ip4) ||
>>>> +        (saddr->proto == htons(ETH_P_IPV6) &&
>>>> +         !ipv6_addr_any(&saddr->u.ip6)))
>>>> +        br_multicast_mark_router(br, port);
>>>>    }
>>>>    static void br_ip4_multicast_query(struct net_bridge *br,
>> Is this also a problem in 4.20?  This patch went into 4.20-rc1, so it
>> has been around for a while with no reported issues that I can find.
>> Any pointers to the reports?
>
> i need to check this. i found this patch in 4.9, 4.14 and 4.4
> the rest was picked up from the mailinglist. according to the git 
> sources of 4.20 and 5.0 the same code is in there as well
>
> i just got the report from users today and was able to reproduce it 
> with iptv streams. just by disabling the code it was working again.
>
> Sebastian
>>
>> thanks,
>>
>> greg k-h
>>
>