From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754136AbdJSNwY (ORCPT ); Thu, 19 Oct 2017 09:52:24 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47772 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753114AbdJSNwV (ORCPT ); Thu, 19 Oct 2017 09:52:21 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Willem de Bruijn , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.4 16/46] packet: in packet_do_bind, test fanout with bind_lock held Date: Thu, 19 Oct 2017 15:48:52 +0200 Message-Id: <20171019134846.409561678@linuxfoundation.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171019134845.293630834@linuxfoundation.org> References: <20171019134845.293630834@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn [ Upstream commit 4971613c1639d8e5f102c4e797c3bf8f83a5a69e ] Once a socket has po->fanout set, it remains a member of the group until it is destroyed. The prot_hook must be constant and identical across sockets in the group. If fanout_add races with packet_do_bind between the test of po->fanout and taking the lock, the bind call may make type or dev inconsistent with that of the fanout group. Hold po->bind_lock when testing po->fanout to avoid this race. I had to introduce artificial delay (local_bh_enable) to actually observe the race. Fixes: dc99f600698d ("packet: Add fanout support.") Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2944,13 +2944,15 @@ static int packet_do_bind(struct sock *s int ret = 0; bool unlisted = false; - if (po->fanout) - return -EINVAL; - lock_sock(sk); spin_lock(&po->bind_lock); rcu_read_lock(); + if (po->fanout) { + ret = -EINVAL; + goto out_unlock; + } + if (name) { dev = dev_get_by_name_rcu(sock_net(sk), name); if (!dev) {