tree 1c3faf15221a588eb099fb7ff2806a6da15c347b
parent c3f9b01849ef3bc69024990092b9f42e20df7797
author Linus Lüssing <linus.luessing@web.de> 1394486724 +0100
committer David S. Miller <davem@davemloft.net> 1394594530 -0400

bridge: multicast: add sanity check for general query destination

General IGMP and MLD queries are supposed to have the multicast
link-local all-nodes address as their destination according to RFC2236
section 9, RFC3376 section 4.1.12/9.1, RFC2710 section 8 and RFC3810
section 5.1.15.

Without this check, such malformed IGMP/MLD queries can result in a
denial of service: The queries are ignored by most IGMP/MLD listeners
therefore they will not respond with an IGMP/MLD report. However,
without this patch these malformed MLD queries would enable the
snooping part in the bridge code, potentially shutting down the
according ports towards these hosts for multicast traffic as the
bridge did not learn about these listeners.

Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>