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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 447ABC47082 for ; Tue, 8 Jun 2021 09:56:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E213611BD for ; Tue, 8 Jun 2021 09:56:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229635AbhFHJ6R (ORCPT ); Tue, 8 Jun 2021 05:58:17 -0400 Received: from mail.netfilter.org ([217.70.188.207]:56064 "EHLO mail.netfilter.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230119AbhFHJ6R (ORCPT ); Tue, 8 Jun 2021 05:58:17 -0400 Received: from netfilter.org (unknown [90.77.255.23]) by mail.netfilter.org (Postfix) with ESMTPSA id D411764133; Tue, 8 Jun 2021 11:55:11 +0200 (CEST) Date: Tue, 8 Jun 2021 11:56:21 +0200 From: Pablo Neira Ayuso To: Phil Sutter Cc: netfilter-devel@vger.kernel.org, Florian Westphal Subject: Re: [nf-next PATCH v2] netfilter: nft_exthdr: Fix for unsafe packet data read Message-ID: <20210608095621.GA15808@salvia> References: <20210608094057.24598-1-phil@nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210608094057.24598-1-phil@nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Tue, Jun 08, 2021 at 11:40:57AM +0200, Phil Sutter wrote: > While iterating through an SCTP packet's chunks, skb_header_pointer() is > called for the minimum expected chunk header size. If (that part of) the > skbuff is non-linear, the following memcpy() may read data past > temporary buffer '_sch'. Use skb_copy_bits() instead which does the > right thing in this situation. > > Fixes: 133dc203d77df ("netfilter: nft_exthdr: Support SCTP chunks") > Suggested-by: Florian Westphal > Signed-off-by: Phil Sutter > --- > Changes since v1: > - skb_copy_bits() call error handling added > --- > net/netfilter/nft_exthdr.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c > index 1b0579cb62d08..7f705b5c09de8 100644 > --- a/net/netfilter/nft_exthdr.c > +++ b/net/netfilter/nft_exthdr.c > @@ -327,7 +327,9 @@ static void nft_exthdr_sctp_eval(const struct nft_expr *expr, > break; > > dest[priv->len / NFT_REG32_SIZE] = 0; > - memcpy(dest, (char *)sch + priv->offset, priv->len); > + if (skb_copy_bits(pkt->skb, offset + priv->offset, > + dest, priv->len) < 0) > + break; Hm, it looks like tcp exthdt matching has the same problem? > return; > } > offset += SCTP_PAD4(ntohs(sch->length)); > -- > 2.31.1 >