From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] udp: fix bcast packet reception Date: Mon, 09 Oct 2017 10:29:18 -0700 (PDT) Message-ID: <20171009.102918.193745106051263192.davem@davemloft.net> References: <66294c8d1c61bdf0bff23a6339a24b4483246caa.1507394363.git.pabeni@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, hannes@stressinduktion.org To: pabeni@redhat.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:52582 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751635AbdJIR3T (ORCPT ); Mon, 9 Oct 2017 13:29:19 -0400 In-Reply-To: <66294c8d1c61bdf0bff23a6339a24b4483246caa.1507394363.git.pabeni@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Paolo Abeni Date: Mon, 9 Oct 2017 14:52:10 +0200 > The commit bc044e8db796 ("udp: perform source validation for > mcast early demux") does not take into account that broadcast packets > lands in the same code path and they need different checks for the > source address - notably, zero source address are valid for bcast > and invalid for mcast. > > As a result, 2nd and later broadcast packets with 0 source address > landing to the same socket are dropped. This breaks dhcp servers. > > Since we don't have stringent performance requirements for ingress > broadcast traffic, fix it by disabling UDP early demux such traffic. > > Reported-by: Hannes Frederic Sowa > Fixes: bc044e8db796 ("udp: perform source validation for mcast early demux") > Signed-off-by: Paolo Abeni Applied and queued up for -stable.