From patchwork Tue May 17 19:21:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 1632520 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=netfilter-devel-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4L2mFK5lyrz9s2R for ; Wed, 18 May 2022 05:21:25 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348534AbiEQTVX (ORCPT ); Tue, 17 May 2022 15:21:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241252AbiEQTVW (ORCPT ); Tue, 17 May 2022 15:21:22 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4342842ED0 for ; Tue, 17 May 2022 12:21:18 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1nr2ku-0003RN-9J; Tue, 17 May 2022 21:21:16 +0200 From: Florian Westphal To: Cc: Florian Westphal , syzbot+4903218f7fba0a2d6226@syzkaller.appspotmail.com, syzbot+afd2d80e495f96049571@syzkaller.appspotmail.com Subject: [PATCH nf-next] netfilter: nfnetlink: fix warn in nfnetlink_unbind Date: Tue, 17 May 2022 21:21:11 +0200 Message-Id: <20220517192111.2080-1-fw@strlen.de> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org syzbot reports following warn: WARNING: CPU: 0 PID: 3600 at net/netfilter/nfnetlink.c:703 nfnetlink_unbind+0x357/0x3b0 net/netfilter/nfnetlink.c:694 The syzbot generated program does this: socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER) = 3 setsockopt(3, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, [1], 4) = 0 ... which triggers 'WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == 0)' check. Instead of counting, just enable reporting for every bind request and check if we still have listeners on unbind. While at it, also add the needed bounds check on nfnl_group2type[] access. Reported-by: Reported-by: Fixes: 2794cdb0b97b ("netfilter: nfnetlink: allow to detect if ctnetlink listeners exist") Signed-off-by: Florian Westphal --- net/netfilter/nfnetlink.c | 24 +++++------------------- 1 file changed, 5 insertions(+), 19 deletions(-) diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index ad3bbe34ca88..2f7c477fc9e7 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -45,7 +45,6 @@ MODULE_DESCRIPTION("Netfilter messages via netlink socket"); static unsigned int nfnetlink_pernet_id __read_mostly; struct nfnl_net { - unsigned int ctnetlink_listeners; struct sock *nfnl; }; @@ -673,18 +672,8 @@ static int nfnetlink_bind(struct net *net, int group) #ifdef CONFIG_NF_CONNTRACK_EVENTS if (type == NFNL_SUBSYS_CTNETLINK) { - struct nfnl_net *nfnlnet = nfnl_pernet(net); - nfnl_lock(NFNL_SUBSYS_CTNETLINK); - - if (WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == UINT_MAX)) { - nfnl_unlock(NFNL_SUBSYS_CTNETLINK); - return -EOVERFLOW; - } - - nfnlnet->ctnetlink_listeners++; - if (nfnlnet->ctnetlink_listeners == 1) - WRITE_ONCE(net->ct.ctnetlink_has_listener, true); + WRITE_ONCE(net->ct.ctnetlink_has_listener, true); nfnl_unlock(NFNL_SUBSYS_CTNETLINK); } #endif @@ -694,15 +683,12 @@ static int nfnetlink_bind(struct net *net, int group) static void nfnetlink_unbind(struct net *net, int group) { #ifdef CONFIG_NF_CONNTRACK_EVENTS - int type = nfnl_group2type[group]; - - if (type == NFNL_SUBSYS_CTNETLINK) { - struct nfnl_net *nfnlnet = nfnl_pernet(net); + if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX) + return; + if (nfnl_group2type[group] == NFNL_SUBSYS_CTNETLINK) { nfnl_lock(NFNL_SUBSYS_CTNETLINK); - WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == 0); - nfnlnet->ctnetlink_listeners--; - if (nfnlnet->ctnetlink_listeners == 0) + if (!nfnetlink_has_listeners(net, group)) WRITE_ONCE(net->ct.ctnetlink_has_listener, false); nfnl_unlock(NFNL_SUBSYS_CTNETLINK); }