From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: Re: [PATCH net/jkirsher] bpf, xdp, i40e: fix i40e_build_skb skb reserve and truesize Date: Wed, 13 Jun 2018 09:26:12 -0700 Message-ID: References: <20180613090436.4266-1-daniel@iogearbox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: intel-wired-lan@lists.osuosl.org, keith.busch@linux.intel.com, makita.toshiaki@lab.ntt.co.jp, bjorn.topel@intel.com, netdev@vger.kernel.org To: Daniel Borkmann , jeffrey.t.kirsher@intel.com Return-path: Received: from mail-it0-f68.google.com ([209.85.214.68]:36125 "EHLO mail-it0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934533AbeFMQ0w (ORCPT ); Wed, 13 Jun 2018 12:26:52 -0400 Received: by mail-it0-f68.google.com with SMTP id j135-v6so4721424itj.1 for ; Wed, 13 Jun 2018 09:26:52 -0700 (PDT) In-Reply-To: <20180613090436.4266-1-daniel@iogearbox.net> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 06/13/2018 02:04 AM, Daniel Borkmann wrote: > Using skb_reserve(skb, I40E_SKB_PAD + (xdp->data - xdp->data_hard_start)) > is clearly wrong since I40E_SKB_PAD already points to the offset where > the original xdp->data was sitting since xdp->data_hard_start is defined > as xdp->data - i40e_rx_offset(rx_ring) where latter offsets to I40E_SKB_PAD > when build skb is used. > > However, also before cc5b114dcf98 ("bpf, i40e: add meta data support") > this seems broken since bpf_xdp_adjust_head() helper could have been used > to alter headroom and enlarge / shrink the frame and with that the assumption > that the xdp->data remains unchanged does not hold and would push a bogus > packet to upper stack. > > ixgbe got this right in 924708081629 ("ixgbe: add XDP support for pass and > drop actions"). In any case, fix it by removing the I40E_SKB_PAD from both > skb_reserve() and truesize calculation. > > Fixes: cc5b114dcf98 ("bpf, i40e: add meta data support") > Fixes: 0c8493d90b6b ("i40e: add XDP support for pass and drop actions") > Reported-by: Keith Busch > Reported-by: Toshiaki Makita > Signed-off-by: Daniel Borkmann > Cc: Björn Töpel > Cc: John Fastabend > --- > drivers/net/ethernet/intel/i40e/i40e_txrx.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > Thanks! I missed this during review. Acked-by: John Fastabend