From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754081Ab1AYVcI (ORCPT ); Tue, 25 Jan 2011 16:32:08 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36985 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753581Ab1AYVcG (ORCPT ); Tue, 25 Jan 2011 16:32:06 -0500 Date: Tue, 25 Jan 2011 13:32:40 -0800 (PST) Message-Id: <20110125.133240.59688304.davem@davemloft.net> To: toshiharu-linux@dsn.okisemi.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, qi.wang@intel.com, yong.y.wang@intel.com, andrew.chih.howe.khor@intel.com, joel.clark@intel.com, kok.howg.ewe@intel.com Subject: Re: [PATCH] pch_gbe: Fix the issue that the receiving data is not normal. From: David Miller In-Reply-To: <4D3D0373.30003@dsn.okisemi.com> References: <4D3D0373.30003@dsn.okisemi.com> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Toshiharu Okada Date: Mon, 24 Jan 2011 13:43:31 +0900 > This PCH_GBE driver had an issue that the receiving data is not normal. > This driver had not removed correctly the padding data > which the DMA include in receiving data. > > This patch fixed this issue. > > Signed-off-by: Toshiharu Okada There are bugs in these changes: > if (skb_copy_flag) { /* recycle skb */ > struct sk_buff *new_skb; > new_skb = > - netdev_alloc_skb(netdev, > - length + NET_IP_ALIGN); > + netdev_alloc_skb(netdev, length); > if (new_skb) { > if (!skb_padding_flag) { > skb_reserve(new_skb, > - NET_IP_ALIGN); > + PCH_GBE_DMA_PADDING); > } > memcpy(new_skb->data, skb->data, > length); If "!skb_padding_flag" then you will write past the end of the SKB data in that memcpy. You cannot allocate only "length" then proceed to reserve PCH_GBE_DMA_PADDING and then add "length" worth of data on top of that. In such a cause you must allocate at least "length + PCH_GBE_DMA_PADDING". Furthermore you _MUST_ respect NET_IP_ALIGN. Some platforms set this value to "0", because otherwise performance suffers greatly. There are two seperate issues, removing the padding bytes provided by the device, and aligning the IP headers as wanted by the cpu architecutre. Therefore they should be handled seperately, and we therefore should still see references to NET_IP_ALIGN in your patch.