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=-10.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 3E87AC43612 for ; Fri, 11 Jan 2019 14:16:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 074C021783 for ; Fri, 11 Jan 2019 14:16:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547216178; bh=29JBosk4c3L8W3RynSufGSeHJ2LBn3Zbr2+n3uCtt14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dJyyTAdi+BzOWu3+zy2bp5CoAaqpw+wk4fll1guZpjKIz4gSeRbWABlQbIUQvt1BB J5V69uF1w2xis30qJlZTIeKsi/yJOjq+l0mhlgszdpWezRDaWFeTjyLtbIE9Lug+3C RNw3ygFOZV0qQxcvukxsVWaZVkBXvDU2WN9drZzA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387608AbfAKOQR (ORCPT ); Fri, 11 Jan 2019 09:16:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:60632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387589AbfAKOQQ (ORCPT ); Fri, 11 Jan 2019 09:16:16 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 60AEC21783; Fri, 11 Jan 2019 14:16:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547216175; bh=29JBosk4c3L8W3RynSufGSeHJ2LBn3Zbr2+n3uCtt14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=doiosiCfhZ5hi9uvCAEUbIoML1de6qX3OlVVsBoIG2P/LNUQtSQfoB4PPcEMEmNL6 xMc6RYbW3Mv1uPeJ7daM/or50LpJ0pSQWQw38Q+X4yJfzTlcvzq1D0roisfG9RYJFx 1OiPWLeeZ0gBMe7BvqZZQ63q1iQXX3xbggem5iaU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , "David S. Miller" Subject: [PATCH 3.18 16/47] vhost: make sure used idx is seen before log in vhost_add_used_n() Date: Fri, 11 Jan 2019 15:08:01 +0100 Message-Id: <20190111130958.060804757@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190111130956.170952125@linuxfoundation.org> References: <20190111130956.170952125@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang [ Upstream commit 841df922417eb82c835e93d4b93eb6a68c99d599 ] We miss a write barrier that guarantees used idx is updated and seen before log. This will let userspace sync and copy used ring before used idx is update. Fix this by adding a barrier before log_write(). Fixes: 8dd014adfea6f ("vhost-net: mergeable buffers support") Acked-by: Michael S. Tsirkin Signed-off-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/vhost.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1409,6 +1409,8 @@ int vhost_add_used_n(struct vhost_virtqu return -EFAULT; } if (unlikely(vq->log_used)) { + /* Make sure used idx is seen before log. */ + smp_wmb(); /* Log used index update. */ log_write(vq->log_base, vq->log_addr + offsetof(struct vring_used, idx),