From patchwork Wed Apr 11 02:35:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 10334775 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0DCA36029B for ; Wed, 11 Apr 2018 02:36:36 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F3BF928446 for ; Wed, 11 Apr 2018 02:36:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E5CB62846C; Wed, 11 Apr 2018 02:36:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7691B28446 for ; Wed, 11 Apr 2018 02:36:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752870AbeDKCf5 (ORCPT ); Tue, 10 Apr 2018 22:35:57 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54078 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752850AbeDKCf4 (ORCPT ); Tue, 10 Apr 2018 22:35:56 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D6B924075A66; Wed, 11 Apr 2018 02:35:55 +0000 (UTC) Received: from localhost (ovpn-116-59.ams2.redhat.com [10.36.116.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0393084452; Wed, 11 Apr 2018 02:35:49 +0000 (UTC) From: Stefan Hajnoczi To: virtualization@lists.linux-foundation.org Cc: Linus Torvalds , jasowang@redhat.com, mst@redhat.com, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Stefan Hajnoczi Subject: [PATCH v3 1/2] vhost: fix vhost_vq_access_ok() log check Date: Wed, 11 Apr 2018 10:35:40 +0800 Message-Id: <20180411023541.15776-2-stefanha@redhat.com> In-Reply-To: <20180411023541.15776-1-stefanha@redhat.com> References: <20180411023541.15776-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Wed, 11 Apr 2018 02:35:55 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Wed, 11 Apr 2018 02:35:55 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'stefanha@redhat.com' RCPT:'' Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Commit d65026c6c62e7d9616c8ceb5a53b68bcdc050525 ("vhost: validate log when IOTLB is enabled") introduced a regression. The logic was originally: if (vq->iotlb) return 1; return A && B; After the patch the short-circuit logic for A was inverted: if (A || vq->iotlb) return A; return B; This patch fixes the regression by rewriting the checks in the obvious way, no longer returning A when vq->iotlb is non-NULL (which is hard to understand). Reported-by: syzbot+65a84dde0214b0387ccd@syzkaller.appspotmail.com Cc: Jason Wang Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index bec722e41f58..fc805b7fad9d 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1244,10 +1244,12 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq, /* Caller should have vq mutex and device mutex */ int vhost_vq_access_ok(struct vhost_virtqueue *vq) { - int ret = vq_log_access_ok(vq, vq->log_base); + if (!vq_log_access_ok(vq, vq->log_base)) + return 0; - if (ret || vq->iotlb) - return ret; + /* Access validation occurs at prefetch time with IOTLB */ + if (vq->iotlb) + return 1; return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); }