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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 D2089C433DB for ; Wed, 3 Feb 2021 10:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9434164F50 for ; Wed, 3 Feb 2021 10:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233970AbhBCKpx (ORCPT ); Wed, 3 Feb 2021 05:45:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233932AbhBCKpu (ORCPT ); Wed, 3 Feb 2021 05:45:50 -0500 Received: from orbyte.nwl.cc (orbyte.nwl.cc [IPv6:2001:41d0:e:133a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DABBCC061573 for ; Wed, 3 Feb 2021 02:45:09 -0800 (PST) Received: from n0-1 by orbyte.nwl.cc with local (Exim 4.94) (envelope-from ) id 1l7Fel-0003KG-N8; Wed, 03 Feb 2021 11:45:07 +0100 Date: Wed, 3 Feb 2021 11:45:07 +0100 From: Phil Sutter To: Pablo Neira Ayuso Cc: netfilter-devel@vger.kernel.org Subject: Re: [nft PATCH] erec: Sanitize erec location indesc Message-ID: <20210203104507.GO3158@orbyte.nwl.cc> Mail-Followup-To: Phil Sutter , Pablo Neira Ayuso , netfilter-devel@vger.kernel.org References: <20210126175502.9171-1-phil@nwl.cc> <20210203003832.GA30866@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210203003832.GA30866@salvia> Sender: Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi Pablo, 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"); and this ruleset: | table netdev t { | chain c { | reject | } | } Cheers, Phil