From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752593AbeC2Ms0 (ORCPT ); Thu, 29 Mar 2018 08:48:26 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34612 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751008AbeC2MsY (ORCPT ); Thu, 29 Mar 2018 08:48:24 -0400 Date: Thu, 29 Mar 2018 15:48:22 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] vhost: validate log when IOTLB is enabled Message-ID: <20180329154803-mutt-send-email-mst@kernel.org> References: <1522310404-8486-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522310404-8486-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 29, 2018 at 04:00:04PM +0800, Jason Wang wrote: > Vq log_base is the userspace address of bitmap which has nothing to do > with IOTLB. So it needs to be validated unconditionally otherwise we > may try use 0 as log_base which may lead to pin pages that will lead > unexpected result (e.g trigger BUG_ON() in set_bit_to_user()). > > Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API") > Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin stable material I guess. > --- > drivers/vhost/vhost.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 5d5a9d9..5320039 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1244,14 +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) > { > - if (vq->iotlb) { > - /* When device IOTLB was used, the access validation > - * will be validated during prefetching. > - */ > - return 1; > - } > - return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) && > - vq_log_access_ok(vq, vq->log_base); > + int ret = vq_log_access_ok(vq, vq->log_base); > + > + if (ret || vq->iotlb) > + return ret; > + > + return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); > } > EXPORT_SYMBOL_GPL(vhost_vq_access_ok); > > -- > 2.7.4