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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 E4916C4338F for ; Tue, 24 Aug 2021 01:04:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC176613DB for ; Tue, 24 Aug 2021 01:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234293AbhHXBDU (ORCPT ); Mon, 23 Aug 2021 21:03:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:47770 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233986AbhHXA5N (ORCPT ); Mon, 23 Aug 2021 20:57:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 77560617E2; Tue, 24 Aug 2021 00:55:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629766542; bh=qhESlreqaguGA6UjYwAFl9MniaY/yGL8vZMgJ69S/zY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KQcbf4OsSTUMWcexDJg6LKYFdW3xQkGX3kgU+bF+RK7rtq8V3yTdKqSGfjLTc2yy5 oNggMYYiZfu+3lXKiBg5ZZcVCTVIjQDvuXYh/cFCVMQK2Wfbjmerq9v1YI9O0MbLKJ 0ty5wfylSsCfyJ7NfYgWnaWwO2TPVewZnxp/cKhQFS5W4fXrutBTVo9Oo3oeoVfAc8 sAvLbUADY3bxqHUyydwKB+6t1UdmEZ9Cc6OVcdqXd5lkMA7b3glwniedZKhFn4O39T 7M99vaYyn9+1on7XsSsByB3Eqr6XwnnKtjWqR6qYFKOhIQq4i0pk2AUZQJKK7+Qbm5 7aHEzv0PWnXkw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Neeraj Upadhyay , Jason Wang , Stefano Garzarella , "Michael S . Tsirkin" , Sasha Levin , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 2/3] vringh: Use wiov->used to check for read/write desc order Date: Mon, 23 Aug 2021 20:55:38 -0400 Message-Id: <20210824005539.631820-2-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824005539.631820-1-sashal@kernel.org> References: <20210824005539.631820-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 d56736655dec..da47542496cc 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -329,7 +329,7 @@ __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