Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1426744AbdD2JjL (ORCPT ); Sat, 29 Apr 2017 05:39:11 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:5902 "EHLO dggrg03-dlp.huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1425976AbdD2JjH (ORCPT ); Sat, 29 Apr 2017 05:39:07 -0400 Subject: Re: [PATCH v2] iov_iter: don't revert iov buffer if csum error To: Al Viro References: <20170429024647.GO29622@ZenIV.linux.org.uk> CC: David Miller , , , , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , LinuxArm , "weiyongjun (A)" From: Ding Tianhong Message-ID: <0cc7c1d2-87d0-6cc4-624b-1cf96678bfd7@huawei.com> Date: Sat, 29 Apr 2017 17:37:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20170429024647.GO29622@ZenIV.linux.org.uk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.23.32] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020206.59045EED.0062,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: af45c27843dfcd0da2a7c06d5775acfb Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 986 Lines: 40 On 2017/4/29 10:46, Al Viro wrote: > On Sat, Apr 29, 2017 at 10:38:48AM +0800, Ding Tianhong wrote: >> The patch 327868212381 (make skb_copy_datagram_msg() et.al. preserve >> ->msg_iter on error) will revert the iov buffer if copy to iter >> failed, but it didn't copy any datagram if the skb_checksum_complete >> error, so no need to revert any data at this place. > > The bug is real, but I would suggest a simpler fix: > if (__skb_checksum_complete(skb)) > return -EINVAL; > leaving the rest as-is. > Looks good, if so, we don't need the csum_error any more, - if (csum_fold(csum)) + + if (csum_fold(csum)) { + iov_iter_revert(&msg->msg_iter, chunk); + return -EINVAL; + } + if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) netdev_rx_csum_fault(skb->dev); } return 0; - csum_error: - iov_iter_revert(&msg->msg_iter, chunk); - return -EINVAL; fault: return -EFAULT; DO you agree this way? :) Thanks Ding > . >