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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 06C23C43216 for ; Wed, 1 Sep 2021 12:31:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E680E610E5 for ; Wed, 1 Sep 2021 12:31:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245548AbhIAMcs (ORCPT ); Wed, 1 Sep 2021 08:32:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:33218 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244898AbhIAMbi (ORCPT ); Wed, 1 Sep 2021 08:31:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1BAE460BD3; Wed, 1 Sep 2021 12:30:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1630499441; bh=MRtasKcZC6zA0u1WWKSlS/dxg7gw7FIhvKi51Z/23H0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0P87YW9hqyvrYvlF9T/as/tN4uvi8uAxAvtnY6quS0B7lqE7VcqtLkbkg6TOLKFF/ eYPkAqwY0lwhRTgR5fdOxtfNK7yhYCOIH7Jx/QBspGfUJNvkkXeKv/X8stPDyd3NGC 8Lnawo/oh92WPEvhjUFzq6yix94BQf0XMoCAklpI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jason Wang , Stefano Garzarella , Neeraj Upadhyay , "Michael S. Tsirkin" , Sasha Levin Subject: [PATCH 4.19 23/33] vringh: Use wiov->used to check for read/write desc order Date: Wed, 1 Sep 2021 14:28:12 +0200 Message-Id: <20210901122251.559729349@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210901122250.752620302@linuxfoundation.org> References: <20210901122250.752620302@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Neeraj Upadhyay [ Upstream commit e74cfa91f42c50f7f649b0eca46aa049754ccdbd ] As __vringh_iov() traverses a descriptor chain, it populates each descriptor entry into either read or write vring iov and increments that iov's ->used member. So, as we iterate over a descriptor chain, at any point, (riov/wriov)->used value gives the number of descriptor enteries available, which are to be read or written by the device. As all read iovs must precede the write iovs, wiov->used should be zero when we are traversing a read descriptor. Current code checks for wiov->i, to figure out whether any previous entry in the current descriptor chain was a write descriptor. However, iov->i is only incremented, when these vring iovs are consumed, at a later point, and remain 0 in __vringh_iov(). So, correct the check for read and write descriptor order, to use wiov->used. Acked-by: Jason Wang Reviewed-by: Stefano Garzarella Signed-off-by: Neeraj Upadhyay Link: https://lore.kernel.org/r/1624591502-4827-1-git-send-email-neeraju@codeaurora.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin --- drivers/vhost/vringh.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index 59c61744dcc1..97aa9b87e572 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -330,7 +330,7 @@ __vringh_iov(struct vringh *vrh, u16 i, iov = wiov; else { iov = riov; - if (unlikely(wiov && wiov->i)) { + if (unlikely(wiov && wiov->used)) { vringh_bad("Readable desc %p after writable", &descs[i]); err = -EINVAL; -- 2.30.2