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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 E022DC433F5 for ; Fri, 7 Sep 2018 21:13:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D5892075E for ; Fri, 7 Sep 2018 21:13:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D5892075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728132AbeIHB4U (ORCPT ); Fri, 7 Sep 2018 21:56:20 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40784 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727349AbeIHB4U (ORCPT ); Fri, 7 Sep 2018 21:56:20 -0400 Received: from localhost (ip-213-127-74-90.ip.prioritytelecom.net [213.127.74.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 9AFACF07; Fri, 7 Sep 2018 21:13:33 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chirantan Ekbote , Greg Kurz , Dylan Reid , Guenter Roeck , Dominique Martinet Subject: [PATCH 4.18 004/145] 9p/net: Fix zero-copy path in the 9p virtio transport Date: Fri, 7 Sep 2018 23:07:50 +0200 Message-Id: <20180907210904.004099774@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180907210903.617721278@linuxfoundation.org> References: <20180907210903.617721278@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chirantan Ekbote commit d28c756caee6e414d9ba367d0b92da24145af2a8 upstream. The zero-copy optimization when reading or writing large chunks of data is quite useful. However, the 9p messages created through the zero-copy write path have an incorrect message size: it should be the size of the header + size of the data being written but instead it's just the size of the header. This only works if the server ignores the size field of the message and otherwise breaks the framing of the protocol. Fix this by re-writing the message size field with the correct value. Tested by running `dd if=/dev/zero of=out bs=4k count=1` inside a virtio-9p mount. Link: http://lkml.kernel.org/r/20180717003529.114368-1-chirantan@chromium.org Signed-off-by: Chirantan Ekbote Reviewed-by: Greg Kurz Tested-by: Greg Kurz Cc: Dylan Reid Cc: Guenter Roeck Cc: stable@vger.kernel.org Signed-off-by: Dominique Martinet Signed-off-by: Greg Kroah-Hartman --- net/9p/trans_virtio.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -406,6 +406,7 @@ p9_virtio_zc_request(struct p9_client *c p9_debug(P9_DEBUG_TRANS, "virtio request\n"); if (uodata) { + __le32 sz; int n = p9_get_mapped_pages(chan, &out_pages, uodata, outlen, &offs, &need_drop); if (n < 0) @@ -416,6 +417,12 @@ p9_virtio_zc_request(struct p9_client *c memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); outlen = n; } + /* The size field of the message must include the length of the + * header and the length of the data. We didn't actually know + * the length of the data until this point so add it in now. + */ + sz = cpu_to_le32(req->tc->size + outlen); + memcpy(&req->tc->sdata[0], &sz, sizeof(sz)); } else if (uidata) { int n = p9_get_mapped_pages(chan, &in_pages, uidata, inlen, &offs, &need_drop);