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 50437C47082 for ; Tue, 8 Jun 2021 09:15:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3443C6127A for ; Tue, 8 Jun 2021 09:15:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231268AbhFHJRE (ORCPT ); Tue, 8 Jun 2021 05:17:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231363AbhFHJQw (ORCPT ); Tue, 8 Jun 2021 05:16:52 -0400 Received: from Chamillionaire.breakpoint.cc (unknown [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09C02C061787 for ; Tue, 8 Jun 2021 02:15:00 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1lqXop-0008Hc-3X; Tue, 08 Jun 2021 11:14:43 +0200 Date: Tue, 8 Jun 2021 11:14:43 +0200 From: Florian Westphal To: Phil Sutter Cc: Pablo Neira Ayuso , netfilter-devel@vger.kernel.org, Florian Westphal Subject: Re: [nf-next PATCH] netfilter: nft_exthdr: Fix for unsafe packet data read Message-ID: <20210608091443.GE20020@breakpoint.cc> References: <20210608085104.6249-1-phil@nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210608085104.6249-1-phil@nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org 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 > --- > net/netfilter/nft_exthdr.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c > index 1b0579cb62d08..2b976687510d8 100644 > --- a/net/netfilter/nft_exthdr.c > +++ b/net/netfilter/nft_exthdr.c > @@ -327,7 +327,8 @@ 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); > + skb_copy_bits(pkt->skb, offset + priv->offset, > + dest, priv->len); can you 'goto err' when this fails just like other callers in the same file? Thanks!