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=-6.7 required=3.0 tests=BAYES_00,FORGED_MUA_MOZILLA, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS autolearn=no 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 0AFD6C433E0 for ; Tue, 9 Feb 2021 15:54:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4A4C64E75 for ; Tue, 9 Feb 2021 15:54:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232384AbhBIPyF (ORCPT ); Tue, 9 Feb 2021 10:54:05 -0500 Received: from correo.us.es ([193.147.175.20]:51904 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232294AbhBIPyE (ORCPT ); Tue, 9 Feb 2021 10:54:04 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 159112788C2 for ; Tue, 9 Feb 2021 16:53:22 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 006DBDA704 for ; Tue, 9 Feb 2021 16:53:22 +0100 (CET) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id F2979DA73F; Tue, 9 Feb 2021 16:53:21 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id C0A74DA704; Tue, 9 Feb 2021 16:53:19 +0100 (CET) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Tue, 09 Feb 2021 16:53:19 +0100 (CET) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id A039042DC6DD; Tue, 9 Feb 2021 16:53:19 +0100 (CET) Date: Tue, 9 Feb 2021 16:53:19 +0100 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Phil Sutter , netfilter-devel@vger.kernel.org Subject: Re: [nft PATCH] erec: Sanitize erec location indesc Message-ID: <20210209155319.GA29313@salvia> References: <20210126175502.9171-1-phil@nwl.cc> <20210203003832.GA30866@salvia> <20210203104507.GO3158@orbyte.nwl.cc> <20210209131511.GA27807@salvia> <20210209141151.GO3158@orbyte.nwl.cc> <20210209155030.GA16191@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210209155030.GA16191@salvia> User-Agent: Mozilla/5.0 X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Tue, Feb 09, 2021 at 04:50:30PM +0100, Pablo Neira Ayuso wrote: > On Tue, Feb 09, 2021 at 03:11:51PM +0100, Phil Sutter wrote: > > Hi Pablo, > > > > On Tue, Feb 09, 2021 at 02:15:11PM +0100, Pablo Neira Ayuso wrote: > > > On Wed, Feb 03, 2021 at 11:45:07AM +0100, Phil Sutter wrote: > > > > On Wed, Feb 03, 2021 at 01:38:32AM +0100, Pablo Neira Ayuso wrote: > > > > > On Tue, Jan 26, 2021 at 06:55:02PM +0100, Phil Sutter wrote: > > > > > > erec_print() unconditionally dereferences erec->locations->indesc, so > > > > > > make sure it is valid when either creating an erec or adding a location. > > > > > > > > > > I guess your're trigger a bug where erec is indesc is NULL, thing is > > > > > that indesc should be always set on. Is there a reproducer for this bug? > > > > > > > > Yes, exactly. I hit it when trying to clean up the netdev family reject > > > > support, while just "hacking around". You can trigger it with the > > > > following change: > > > > > > > > | --- a/src/evaluate.c > > > > | +++ b/src/evaluate.c > > > > | @@ -2718,7 +2718,7 @@ static int stmt_evaluate_reject_bridge(struct eval_ctx *ctx, struct stmt *stmt, > > > > | const struct proto_desc *desc; > > > > | > > > > | desc = ctx->pctx.protocol[PROTO_BASE_LL_HDR].desc; > > > > | - if (desc != &proto_eth && desc != &proto_vlan && desc != &proto_netdev) > > > > | + if (desc != &proto_eth && desc != &proto_vlan) > > > > | return stmt_binary_error(ctx, > > > > | &ctx->pctx.protocol[PROTO_BASE_LL_HDR], > > > > | stmt, "unsupported link layer protocol"); > > > > > > I'm attaching fix. > > > > > > Looks like call to stmt_binary_error() parameters are not in the right > > > order, &ctx->pctx.protocol[PROTO_BASE_LL_HDR] has indesc. > > > > Thanks for addressing the root problem! > > > > > Probably add a bugtrap to erec to check that indesc is always set on > > > accordingly instead? > > > > Is it better than just sanitizing input to error functions? After all we > > just want to make sure users see the error message, right? Catching > > the programming mistake (wrong args passed to __stmt_binary_error()) > > IMHO is useful only if we can compile-time assert it. Otherwise we risk > > hiding error info from user. > > I see. I don't see a way to catch this at compile time. > > Push out your patch and I'll push mine too for correctness. Hm, one second: Probably set internal_indesc for autogenerated dependencies?