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=unavailable 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 933C7C43387 for ; Fri, 11 Jan 2019 14:27:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5AB972177B for ; Fri, 11 Jan 2019 14:27:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547216837; bh=7bejs3B16iSuZbRrTu9WGztmuBTH/L7qAylzwkvnyM8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VjRLjC/xQwIHKE+KKKKUimYhu1aMfr7SVuLJ+DUipyZHxS3ug6DCBBB77gykM8zcC TkR2NoPfql4wbNEYsExbsTLOSSGW0UnAwiC4C4lBXHNuHR8dvceB7Lbh/NJ1Fge8bM ZzkM4PfC72n3NeIZ7cU/npdVhqiw8seSEnRsXEUg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387838AbfAKORQ (ORCPT ); Fri, 11 Jan 2019 09:17:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:33650 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731797AbfAKORP (ORCPT ); Fri, 11 Jan 2019 09:17:15 -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 EB8FA21783; Fri, 11 Jan 2019 14:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547216235; bh=7bejs3B16iSuZbRrTu9WGztmuBTH/L7qAylzwkvnyM8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iRYth+cSeTV6a6WiAGwTikUvRIf4sdiqkH7WOoUQ//IIN7qLfCZoob6V7D69y0Bzw 3guw38kpRy6AGtz0dUF4OYls2xcTso2Mr43wKV9Pm7pTF10Dka41gVl0RrnnOsjADd A6gDnxdFjQ6W5qMpWKROOfVOmg/hQ4UarXa/eVyQ= 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 4.4 25/88] vhost: make sure used idx is seen before log in vhost_add_used_n() Date: Fri, 11 Jan 2019 15:07:54 +0100 Message-Id: <20190111131049.892813367@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190111131045.137499039@linuxfoundation.org> References: <20190111131045.137499039@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 4.4-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 @@ -1550,6 +1550,8 @@ 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),