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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 A3E2BC4338F for ; Sun, 8 Aug 2021 16:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DBF461004 for ; Sun, 8 Aug 2021 16:16:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231755AbhHHQQu (ORCPT ); Sun, 8 Aug 2021 12:16:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:50712 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230049AbhHHQQu (ORCPT ); Sun, 8 Aug 2021 12:16:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628439390; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gxiT4tHPMMwG4z1tnV753/NcwtQf2gEijqfbmiwYjJI=; b=Bo46Vf0rZW2tyLv4F2YgXE9pGTZXC6ILMueJycb9h+b9MgLTm7bP2EOC2lpEAS5blKkzYq mXSRt0mgPVBldLjHAPXz0jBoSUH6juMsbCnwjg2fJGqi8NG8ceSkkMsOQYhvztLdyo5Scz OzLcViCx5vu1jNUpW8X1jja5dpBYTIE= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-567-AWpCo4VENFCJnFnjmWA4eQ-1; Sun, 08 Aug 2021 12:16:29 -0400 X-MC-Unique: AWpCo4VENFCJnFnjmWA4eQ-1 Received: by mail-wm1-f71.google.com with SMTP id 21-20020a05600c0255b02902571fa93802so3807255wmj.1 for ; Sun, 08 Aug 2021 09:16:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=gxiT4tHPMMwG4z1tnV753/NcwtQf2gEijqfbmiwYjJI=; b=djWgqrtml+sX+6kfOBkB86n0lI9KiLku0svEro/xpwzbESkv3OhO3ktyhulmt0HUtT XM2JlbB1rYNQmclTn5XfVNClohzUB2ulDcsJO25mwJr+JEaRB9NDIP+vobb1gAZ6r3gY HY0mR000xKs7ZNdOKGT77NqA3GRUzBB+8VePf+/08GgyR3MLCkyNkFPq7CxpZM34Fue2 ++o+k+N8jlRZvF4PMFx/I5KlvBzGONo/2tkGTyAH2uRhQuQehlnEEWazVfIcOuD3qBHK ao/ul3lDp+khXB3xJiAe86whw2FfoylNxZTsLpKkEe+ZeG3d0isyDyXZiMqv1BGclPz8 f/IQ== X-Gm-Message-State: AOAM531hGkjw6AvVwaUHe+ECxo7Uua46IAIFA+JcGomvpvaGa5JbX/14 FcBrxGMi5En7nT22ASgXiiLXV49vxVfIK0vHUn4i4B2ie5gRWcReS8DRlrfvwmV0qsnHzJqOULT 4q1+HsVc88OFLSnSi X-Received: by 2002:adf:d1c7:: with SMTP id b7mr20740636wrd.108.1628439388250; Sun, 08 Aug 2021 09:16:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxO0fhr9qI/x9zK6sthJtFPyyWDA7xREtChOJN8gIcNtx8Y+SSOVqVsLvMAy27JPOjN0VETCw== X-Received: by 2002:adf:d1c7:: with SMTP id b7mr20740622wrd.108.1628439388053; Sun, 08 Aug 2021 09:16:28 -0700 (PDT) Received: from pc-32.home (2a01cb058918ce00dd1a5a4f9908f2d5.ipv6.abo.wanadoo.fr. [2a01:cb05:8918:ce00:dd1a:5a4f:9908:f2d5]) by smtp.gmail.com with ESMTPSA id y19sm18905827wmq.5.2021.08.08.09.16.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Aug 2021 09:16:27 -0700 (PDT) Date: Sun, 8 Aug 2021 18:16:25 +0200 From: Guillaume Nault To: Jakub Kicinski Cc: David Miller , netdev@vger.kernel.org, Martin Varghese , Willem de Bruijn Subject: Re: [PATCH net] bareudp: Fix invalid read beyond skb's linear data Message-ID: <20210808161625.GA2912@pc-32.home> References: <7741c46545c6ef02e70c80a9b32814b22d9616b3.1628264975.git.gnault@redhat.com> <20210806162234.69334902@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210806162234.69334902@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Aug 06, 2021 at 04:22:34PM -0700, Jakub Kicinski wrote: > On Fri, 6 Aug 2021 17:52:06 +0200 Guillaume Nault wrote: > > Data beyond the UDP header might not be part of the skb's linear data. > > Use skb_copy_bits() instead of direct access to skb->data+X, so that > > we read the correct bytes even on a fragmented skb. > > > > Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") > > Signed-off-by: Guillaume Nault > > --- > > drivers/net/bareudp.c | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c > > index a7ee0af1af90..54e321a695ce 100644 > > --- a/drivers/net/bareudp.c > > +++ b/drivers/net/bareudp.c > > @@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) > > family = AF_INET6; > > > > if (bareudp->ethertype == htons(ETH_P_IP)) { > > - struct iphdr *iphdr; > > + __u8 ipversion; > > > > - iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN); > > - if (iphdr->version == 4) { > > - proto = bareudp->ethertype; > > - } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) { > > + if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion, > > + sizeof(ipversion))) { > > No preference just curious - could skb_header_pointer() be better suited? I have no preference either. I just used skb_copy_bits() because it didn't seem useful to get a pointer to the buffer (just to read one byte of data). But I don't mind reposting with skb_header_pointer() if anyone prefers that solution.