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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 C4B4EC43331 for ; Mon, 30 Mar 2020 14:39:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9789F206DB for ; Mon, 30 Mar 2020 14:39:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728465AbgC3Oja (ORCPT ); Mon, 30 Mar 2020 10:39:30 -0400 Received: from a.mx.secunet.com ([62.96.220.36]:59484 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727183AbgC3Oja (ORCPT ); Mon, 30 Mar 2020 10:39:30 -0400 Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id B5ADD20523; Mon, 30 Mar 2020 16:39:29 +0200 (CEST) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Fx4aNTChbPxE; Mon, 30 Mar 2020 16:39:29 +0200 (CEST) Received: from cas-essen-02.secunet.de (202.40.53.10.in-addr.arpa [10.53.40.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id 4990C2006F; Mon, 30 Mar 2020 16:39:29 +0200 (CEST) Received: from gauss2.secunet.de (10.182.7.193) by cas-essen-02.secunet.de (10.53.40.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Mon, 30 Mar 2020 16:39:29 +0200 Received: by gauss2.secunet.de (Postfix, from userid 1000) id D868C3180136; Mon, 30 Mar 2020 16:39:28 +0200 (CEST) Date: Mon, 30 Mar 2020 16:39:28 +0200 From: Steffen Klassert To: Florian Westphal CC: Xin Long , network dev , , Paolo Abeni Subject: Re: [PATCH net] udp: fix a skb extensions leak Message-ID: <20200330143928.GN13121@gauss3.secunet.de> References: <20200330132759.GA31510@strlen.de> <20200330134531.GK13121@gauss3.secunet.de> <20200330141147.GC23604@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20200330141147.GC23604@breakpoint.cc> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: cas-essen-02.secunet.de (10.53.40.202) To cas-essen-02.secunet.de (10.53.40.202) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Mar 30, 2020 at 04:11:47PM +0200, Florian Westphal wrote: > Steffen Klassert wrote: > > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > > index 621b4479fee1..7e29590482ce 100644 > > > --- a/net/core/skbuff.c > > > +++ b/net/core/skbuff.c > > > @@ -3668,6 +3668,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, > > > > > > skb_push(nskb, -skb_network_offset(nskb) + offset); > > > > > > + skb_release_head_state(nskb); > > > __copy_skb_header(nskb, skb); > > > > > > skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb)); > > > > > > AFAICS we not only leak reference of extensions, but also skb->dst and skb->_nfct. > > > > Would be nice if we would not need to drop the resources > > just to add them back again in the next line. But it is ok > > as a quick fix for the bug. > > Yes, but are these the same resources? AFAIU thats not the case, i.e. > the skb on fraglist can have different skb->{dst,extension,_nfct} data > than the skb head one, and we can't tell if that data is still valid > (rerouting for example). Some are the same, others not. Originally, I used a subset of __copy_skb_header here. But decided then to use __copy_skb_header to make sure I don't forget anything. So this fix is ok for now.