From: Stefan Hajnoczi <stefanha@redhat.com>
To: Stefano Garzarella <sgarzare@redhat.com>
Cc: virtualization@lists.linux-foundation.org,
Xie Yongji <xieyongji@bytedance.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Laurent Vivier <lvivier@redhat.com>,
linux-kernel@vger.kernel.org, Max Gurtovoy <mgurtovoy@nvidia.com>,
Jason Wang <jasowang@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH RFC v2 08/10] vdpa: add vdpa simulator for block device
Date: Wed, 3 Feb 2021 16:45:51 +0000 [thread overview]
Message-ID: <20210203164551.GG74271@stefanha-x1.localdomain> (raw)
In-Reply-To: <20210202154950.g3rclpigyaigzfgo@steredhat>
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On Tue, Feb 02, 2021 at 04:49:50PM +0100, Stefano Garzarella wrote:
> On Tue, Feb 02, 2021 at 09:34:12AM +0000, Stefan Hajnoczi wrote:
> > On Thu, Jan 28, 2021 at 03:41:25PM +0100, Stefano Garzarella wrote:
> > > +static void vdpasim_blk_work(struct work_struct *work)
> > > +{
> > > + struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
> > > + u8 status = VIRTIO_BLK_S_OK;
> > > + int i;
> > > +
> > > + spin_lock(&vdpasim->lock);
> > > +
> > > + if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
> > > + goto out;
> > > +
> > > + for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
> > > + struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
> > > +
> > > + if (!vq->ready)
> > > + continue;
> > > +
> > > + while (vringh_getdesc_iotlb(&vq->vring, &vq->out_iov,
> > > + &vq->in_iov, &vq->head,
> > > + GFP_ATOMIC) > 0) {
> > > + int write;
> > > +
> > > + vq->in_iov.i = vq->in_iov.used - 1;
> > > + write = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
> > > + &status, 1);
> > > + if (write <= 0)
> > > + break;
> >
> > This code looks fragile:
> >
> > 1. Relying on unsigned underflow and the while loop in
> > vringh_iov_push_iotlb() to handle the case where in_iov.used == 0 is
> > risky and could break.
> >
> > 2. Does this assume that the last in_iov element has size 1? For
> > example, the guest driver may send a single "in" iovec with size 513
> > when reading 512 bytes (with an extra byte for the request status).
> >
> > Please validate inputs fully, even in test/development code, because
> > it's likely to be copied by others when writing production code (or
> > deployed in production by unsuspecting users) :).
>
> Perfectly agree on that, so I addressed these things, also following your
> review on the previous version, on the next patch of this series:
> "vdpa_sim_blk: implement ramdisk behaviour".
>
> Do you think should I move these checks in this patch?
>
> I did this to leave Max credit for this patch and add more code to emulate a
> ramdisk in later patches.
You could update the commit description so it's clear that input
validation is missing and will be added in the next commit.
Stefan
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next prev parent reply other threads:[~2021-02-03 16:47 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 14:41 [PATCH RFC v2 00/10] vdpa: add vdpa simulator for block device Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 01/10] vdpa_sim: use iova module to allocate IOVA addresses Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 02/10] vringh: add 'iotlb_lock' to synchronize iotlb accesses Stefano Garzarella
2021-01-29 7:43 ` Jason Wang
[not found] ` <20210129091850.gatf3ih3knw2p4l4@steredhat>
2021-02-01 6:31 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 03/10] vringh: reset kiov 'consumed' field in __vringh_iov() Stefano Garzarella
2021-02-01 5:40 ` Jason Wang
2021-02-01 10:21 ` Stefano Garzarella
2021-02-02 3:26 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 04/10] vringh: implement vringh_kiov_advance() Stefano Garzarella
2021-02-01 5:43 ` Jason Wang
2021-02-01 10:23 ` Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 05/10] vringh: add vringh_kiov_length() helper Stefano Garzarella
2021-02-01 5:46 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 06/10] vdpa_sim: cleanup kiovs in vdpasim_free() Stefano Garzarella
2021-02-01 5:47 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 07/10] vdpa: Remove the restriction that only supports virtio-net devices Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 08/10] vdpa: add vdpa simulator for block device Stefano Garzarella
2021-01-31 15:31 ` Max Gurtovoy
2021-02-01 8:29 ` Stefano Garzarella
2021-02-01 5:50 ` Jason Wang
2021-02-02 9:34 ` Stefan Hajnoczi
2021-02-02 15:49 ` Stefano Garzarella
2021-02-03 16:45 ` Stefan Hajnoczi [this message]
2021-02-04 8:02 ` Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 09/10] vdpa_sim_blk: implement ramdisk behaviour Stefano Garzarella
2021-02-01 6:03 ` Jason Wang
2021-02-02 9:41 ` Stefan Hajnoczi
2021-01-28 14:41 ` [PATCH RFC v2 10/10] vdpa_sim_blk: handle VIRTIO_BLK_T_GET_ID Stefano Garzarella
2021-02-01 6:04 ` Jason Wang
2021-02-02 9:44 ` Stefan Hajnoczi
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