From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752895AbeDIN6Z (ORCPT ); Mon, 9 Apr 2018 09:58:25 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:39518 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751455AbeDIN6X (ORCPT ); Mon, 9 Apr 2018 09:58:23 -0400 Date: Mon, 9 Apr 2018 16:58:19 +0300 From: "Michael S. Tsirkin" To: Stefan Hajnoczi Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, jasowang@redhat.com, kvm@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] vhost: fix vhost_vq_access_ok() log check Message-ID: <20180409165805-mutt-send-email-mst@kernel.org> References: <20180409131021.5132-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180409131021.5132-1-stefanha@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 09, 2018 at 09:10:21PM +0800, Stefan Hajnoczi wrote: > 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; > > The correct logic is: > > if (!A || vq->iotlb) > return A; > return B; > > Reported-by: syzbot+65a84dde0214b0387ccd@syzkaller.appspotmail.com > Cc: Jason Wang > Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin > --- > drivers/vhost/vhost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 5320039671b7..f6af4210679a 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1246,7 +1246,7 @@ int vhost_vq_access_ok(struct vhost_virtqueue *vq) > { > int ret = vq_log_access_ok(vq, vq->log_base); > > - if (ret || vq->iotlb) > + if (!ret || vq->iotlb) > return ret; > > return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); > -- > 2.14.3