Re: [PATCH net] Bridge: Fix ipv6 mc snooping if bridge has no ipv6 address

From: David Miller
Date: Tue Jun 28 2016 - 08:46:08 EST


From: Linus Lüssing <linus.luessing@xxxxxxxxx>
Date: Sat, 25 Jun 2016 16:20:28 +0200

> On Fri, Jun 24, 2016 at 12:35:18PM +0200, Daniel Danzberger wrote:
>> The bridge is falsly dropping ipv6 mulitcast packets if there is:
>> 1. No ipv6 address assigned on the brigde.
>> 2. No external mld querier present.
>> 3. The internal querier enabled.
>>
>> When the bridge fails to build mld queries, because it has no
>> ipv6 address, it slilently returns, but keeps the local querier enabled.
>> This specific case causes confusing packet loss.
>>
>> Ipv6 multicast snooping can only work if:
>> a) An external querier is present
>> OR
>> b) The bridge has an ipv6 address an is capable of sending own queries
>>
>> Otherwise it has to forward/flood the ipv6 multicast traffic,
>> because snooping cannot work.
>>
>> This patch fixes the issue by adding a flag to the bridge struct that
>> indicates that there is currently no ipv6 address assinged to the bridge
>> and returns a false state for the local querier in
>> __br_multicast_querier_exists().
>
> Fixes: 1d81d4c3dd88 ("bridge: check return value of ipv6_dev_get_saddr()")

You're missing an initial 'd' in that SHA1-ID.

With that fixed, applied and queued up for -stable.