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 47B42C432BE for ; Tue, 24 Aug 2021 00:59:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 315D361165 for ; Tue, 24 Aug 2021 00:59:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233574AbhHXBAN (ORCPT ); Mon, 23 Aug 2021 21:00:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:47756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234603AbhHXA4A (ORCPT ); Mon, 23 Aug 2021 20:56:00 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C077E615A6; Tue, 24 Aug 2021 00:55:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629766503; bh=e9FOK3hE7ppakL8i/xLcGFGvFPB+l0tdIXhg9/AfHQY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tVSD12qOScVsplfydNaQT01a4jXaPP+hUlBmTHnslDwcjI0Em16t7jtVekMutBBXE FKklr2zjjrQTphs0qbTdZCVY1zTRHwrxaU2QkII84nup1XEDkvO7dmgAAKBsSt6wAL vlAHfrVo5Bloz9SXr2T0u7ydbXDvFzhKxo19M0XGyVQnigQinvFch3lUxP3IVqGgnY ai50tKXm62WnZqhJTfwEGXFgvhPaBaqnr6NrZ+QLtju51PcGBW7sclOQdzwtPSgyvY XUzyL2ApR7C90p4MZp/WEh2TnzC0M8EwvgQM+gvrkwXsREV/+Zo2QYebgDv44ax3aj PXFQViXxt3b6g== 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 5.4 04/10] vringh: Use wiov->used to check for read/write desc order Date: Mon, 23 Aug 2021 20:54:51 -0400 Message-Id: <20210824005458.631377-4-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824005458.631377-1-sashal@kernel.org> References: <20210824005458.631377-1-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 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; -- 2.30.2