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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 DE8A9C433DF for ; Thu, 8 Oct 2020 17:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E71722201 for ; Thu, 8 Oct 2020 17:33:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PPpppjTa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732117AbgJHRd5 (ORCPT ); Thu, 8 Oct 2020 13:33:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729179AbgJHRd4 (ORCPT ); Thu, 8 Oct 2020 13:33:56 -0400 Received: from mail-io1-xd41.google.com (mail-io1-xd41.google.com [IPv6:2607:f8b0:4864:20::d41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 122D5C061755 for ; Thu, 8 Oct 2020 10:33:55 -0700 (PDT) Received: by mail-io1-xd41.google.com with SMTP id o17so1523724ioh.9 for ; Thu, 08 Oct 2020 10:33:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Iaeoc6Z+j37l5fM3/LyJnM1wsdflxCQu9r5PHg7l2V8=; b=PPpppjTaYufAXFGB4G5C3WnHczN9a0elI/v2I77ce7Wxk2yalWhX4SmYIqEAe5TUxw +I7KHdt5zDInMGzvbIXNtqI8Ezh4dvfkn/C4c1gIqAMgKpqGwXRfvP4qvkNYBO+rN3a1 sA2GEKcio/GaVqs0aRtr9Jnt99la06etOqyOALHjCNxCPZ9+cDlB//j5OGoiYBb+sI4v YmnLhXo9pWa2+dkC3KVkO7S9xWd8RTEpvDSrc9eSOKkSQ/LcEujn1awLNd11SKMyzApA pNkgeoChKz+q2zqdq/2IYQrMeRo1uKJNGW3DNgoVibHLgf+VQMjSRFD6qkyhXS8tYRGp erFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Iaeoc6Z+j37l5fM3/LyJnM1wsdflxCQu9r5PHg7l2V8=; b=ULS/x5atcAvf47HLWPggSEpj0GTBbliJ9AYRsBq139AUM1NAyJlRifTwX+nmrikUxQ MRRevyLveBbjDXXT32TuLmj5gXtrhSImqwWU9uA0zvxcaOlZEGXm/uhTzPPKQ8ZPOGWM bcQfM5ZsLeoq+51+vrRji3cSroLjGi0Yow9mrbprXmAS+NNoeyt8qydJ07FLwh9jNp9I 9CWzLvGoWDZPUyKUAeedtz5z8KQqFDnb4I9BEnu9fC9ZJwmsP+9VeWNBOBoqZOHJb60i 9F+zlVt9Rfl0FGja/VNgAo/5HyRdQMQPrK1kk56y+29DGwBApfG1Vno+r6XGJSBpUORa tOGA== X-Gm-Message-State: AOAM5320Bd2gT3JcWI1h4mQkKgjHOHbcRsZhZc9NleGdvk83PG0NIVyM Iz9u+7ZEleiC2+g7cvZ//qD0kZh2mPI3i0CvZif2WomlNopIsg== X-Google-Smtp-Source: ABdhPJxskURl0Ygx8QqzgR3khSNO6Kg+BZ+gtfwC6gRTCkfZOFwbnaEZuhkJyPY1th5SufLEJC1Nph0sXChA0zT82qs= X-Received: by 2002:a6b:b446:: with SMTP id d67mr2723243iof.134.1602178434104; Thu, 08 Oct 2020 10:33:54 -0700 (PDT) MIME-Version: 1.0 References: <20201008012154.11149-1-xiyou.wangcong@gmail.com> In-Reply-To: From: Cong Wang Date: Thu, 8 Oct 2020 10:33:43 -0700 Message-ID: Subject: Re: [Patch net] ip_gre: set dev->hard_header_len properly To: Willem de Bruijn Cc: Network Development , syzbot , William Tu , Xie He Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Oct 8, 2020 at 4:49 AM Willem de Bruijn wrote: > > On Wed, Oct 7, 2020 at 9:22 PM Cong Wang wrote: > > > > GRE tunnel has its own header_ops, ipgre_header_ops, and sets it > > conditionally. When it is set, it assumes the outer IP header is > > already created before ipgre_xmit(). > > > > This is not true when we send packets through a raw packet socket, > > where L2 headers are supposed to be constructed by user. Packet > > socket calls dev_validate_header() to validate the header. But > > GRE tunnel does not set dev->hard_header_len, so that check can > > be simply bypassed, therefore uninit memory could be passed down > > to ipgre_xmit(). > > If dev->hard_header_len is zero, the packet socket will not reserve > room for the link layer header, so skb->data points to network_header. > But I don't see any uninitialized packet data? The uninit data is allocated by packet_alloc_skb(), if dev->hard_header_len is 0 and 'len' is anything between [0, tunnel->hlen + sizeof(struct iphdr)), dev_validate_header() still returns true obviously but only 'len' bytes are copied from user-space by skb_copy_datagram_from_iter(). Therefore, those bytes within range (len, tunnel->hlen + sizeof(struct iphdr)] are uninitialized. Thanks.