From patchwork Wed Sep 1 12:28:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 505648 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=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 3A623C432BE for ; Wed, 1 Sep 2021 12:34:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D1D9610FC for ; Wed, 1 Sep 2021 12:34:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344030AbhIAMfK (ORCPT ); Wed, 1 Sep 2021 08:35:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:34264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244662AbhIAMd6 (ORCPT ); Wed, 1 Sep 2021 08:33:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 787A6610CC; Wed, 1 Sep 2021 12:32:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1630499540; bh=e9FOK3hE7ppakL8i/xLcGFGvFPB+l0tdIXhg9/AfHQY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lQ5c94pC3G17aK6AkWxrQUe2TeXvqLC1uAwdJM8fNiidtvx6nJkHRnQ9pmP6p6zN2 U/SMy4hHe7PsAJ0rbsOTxhazmeGYaDjPElXM1Tx+n9c0uzKoYVADTM0rzz7WxbnOTQ HnCAu1mvdQPa91bCiXjdPc0JUrhLfRFmAMYzLOSg= 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 5.4 31/48] vringh: Use wiov->used to check for read/write desc order Date: Wed, 1 Sep 2021 14:28:21 +0200 Message-Id: <20210901122254.434540872@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210901122253.388326997@linuxfoundation.org> References: <20210901122253.388326997@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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 026a37ee4177..4653de001e26 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -331,7 +331,7 @@ __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;