From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCA63C4360F for ; Fri, 5 Apr 2019 08:35:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8167217D7 for ; Fri, 5 Apr 2019 08:35:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="p4H5OXdS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730103AbfDEIfL (ORCPT ); Fri, 5 Apr 2019 04:35:11 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:39182 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729792AbfDEIfK (ORCPT ); Fri, 5 Apr 2019 04:35:10 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x358Y6H6040484; Fri, 5 Apr 2019 08:34:51 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=aZA6nXEd1NSlJuXKjQ1Lm+rqqEs/N+GfF0azZRtkylM=; b=p4H5OXdSgNiG9WNifpk2YyhVJMF4S6+70wn0G+0K0Kb/v7uzdkIm5xHd5/0maJwQjviB rakiUFVEib9f/wOlPpO4ctamok9nSAO82ZsufwD+x5yzqvMzkupoGExPTkHvp2xD/Qcf yoXqW34Q1SFl6p0cskWvLBaISvWV3sCfNCD1hTrPXLsWvEMq9B1rQkrI8H7v+WEIvGyr RoZ+Sfytare78KY+fJwyKRCMaYzkaPcVTf8+s3DNsrpwiEdj1/x9ej/AdO9han1/th48 1r9AZ8kCjN9y2SVMmbFweMXfmhKKwhP3ax/iU8/gX5mKiZBLTiUfry7UwPR8eS+KSfOe gw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2rhyvtkhhj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Apr 2019 08:34:51 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x358Xe6s156966; Fri, 5 Apr 2019 08:34:51 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 2rp3698c44-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Apr 2019 08:34:50 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x358YjPx027118; Fri, 5 Apr 2019 08:34:49 GMT Received: from kadam (/41.202.241.49) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 05 Apr 2019 01:34:45 -0700 Date: Fri, 5 Apr 2019 11:34:37 +0300 From: Dan Carpenter To: Pablo Neira Ayuso Cc: Jozsef Kadlecsik , Florian Westphal , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH] netfilter: nf_tables: prevent shift wrap in nft_chain_parse_hook() Message-ID: <20190405083436.GT32613@kadam> References: <20190402133038.GA18575@kadam> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190402133038.GA18575@kadam> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9217 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904050064 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9217 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904050064 Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Tue, Apr 02, 2019 at 04:30:38PM +0300, Dan Carpenter wrote: > I believe that "hook->num" can be up to UINT_MAX so the shift has to > be unsigned or shifting more than 31 is undefined. It's possible that > this leads to array overflow in nf_tables_addchain(): > > ops->hook = hook.type->hooks[ops->hooknum]; > > Fixes: fe19c04ca137 ("netfilter: nf_tables: remove nhooks field from struct nft_af_info") > Signed-off-by: Dan Carpenter > --- > net/netfilter/nf_tables_api.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c > index ef7772e976cc..b6e48fe7c776 100644 > --- a/net/netfilter/nf_tables_api.c > +++ b/net/netfilter/nf_tables_api.c > @@ -1545,7 +1545,7 @@ static int nft_chain_parse_hook(struct net *net, > if (IS_ERR(type)) > return PTR_ERR(type); > } > - if (!(type->hook_mask & (1 << hook->num))) > + if (!(type->hook_mask & (1U << hook->num))) Ugh... No this doesn't work. It's still undefined behavoir even if we make it unsigned. It has to be: if (hook->num > 31 || !(type->hook_mask & (1 << hook->num))) which seems like a slightly ugly magic number but it fixes the buffer overflow. regards, dan carpenter