From patchwork Sat Aug 15 10:32:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 1345393 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=netfilter.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BTZTy6HRmz9sTF for ; Sun, 16 Aug 2020 08:19:18 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729356AbgHOWTS (ORCPT ); Sat, 15 Aug 2020 18:19:18 -0400 Received: from correo.us.es ([193.147.175.20]:38942 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728861AbgHOWSy (ORCPT ); Sat, 15 Aug 2020 18:18:54 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 32D57DA55D for ; Sat, 15 Aug 2020 12:32:27 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 23DE9DA844 for ; Sat, 15 Aug 2020 12:32:27 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 18543DA73D; Sat, 15 Aug 2020 12:32:27 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on antivirus1-rhel7.int X-Spam-Level: X-Spam-Status: No, score=-108.2 required=7.5 tests=ALL_TRUSTED,BAYES_50, SMTPAUTH_US2,USER_IN_WELCOMELIST,USER_IN_WHITELIST autolearn=disabled version=3.4.1 Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id DD5ADDA72F; Sat, 15 Aug 2020 12:32:24 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Sat, 15 Aug 2020 12:32:24 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from localhost.localdomain (unknown [213.143.48.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: pneira@us.es) by entrada.int (Postfix) with ESMTPSA id F419142EF4E0; Sat, 15 Aug 2020 12:32:23 +0200 (CEST) X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org Subject: [PATCH 8/8] netfilter: ebtables: reject bogus getopt len value Date: Sat, 15 Aug 2020 12:32:01 +0200 Message-Id: <20200815103201.1768-9-pablo@netfilter.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200815103201.1768-1-pablo@netfilter.org> References: <20200815103201.1768-1-pablo@netfilter.org> MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Florian Westphal syzkaller reports splat: ------------[ cut here ]------------ Buffer overflow detected (80 < 137)! Call Trace: do_ebt_get_ctl+0x2b4/0x790 net/bridge/netfilter/ebtables.c:2317 nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116 ip_getsockopt net/ipv4/ip_sockglue.c:1778 [inline] caused by a copy-to-user with a too-large "*len" value. This adds a argument check on *len just like in the non-compat version of the handler. Before the "Fixes" commit, the reproducer fails with -EINVAL as expected: 1. core calls the "compat" getsockopt version 2. compat getsockopt version detects the *len value is possibly in 64-bit layout (*len != compat_len) 3. compat getsockopt version delegates everything to native getsockopt version 4. native getsockopt rejects invalid *len -> compat handler only sees len == sizeof(compat_struct) for GET_ENTRIES. After the refactor, event sequence is: 1. getsockopt calls "compat" version (len != native_len) 2. compat version attempts to copy *len bytes, where *len is random value from userspace Fixes: fc66de8e16ec ("netfilter/ebtables: clean up compat {get, set}sockopt handling") Reported-by: syzbot+5accb5c62faa1d346480@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Reviewed-by: Christoph Hellwig Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/ebtables.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index 1641f414d1ba..ebe33b60efd6 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2238,6 +2238,10 @@ static int compat_do_ebt_get_ctl(struct sock *sk, int cmd, struct ebt_table *t; struct net *net = sock_net(sk); + if ((cmd == EBT_SO_GET_INFO || cmd == EBT_SO_GET_INIT_INFO) && + *len != sizeof(struct compat_ebt_replace)) + return -EINVAL; + if (copy_from_user(&tmp, user, sizeof(tmp))) return -EFAULT;