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Re: [PATCH] vhost: Check for valid vdev in vhost_backend_handle_iotlb_ms
From: |
Eugenio Perez Martin |
Subject: |
Re: [PATCH] vhost: Check for valid vdev in vhost_backend_handle_iotlb_msg |
Date: |
Fri, 29 Jan 2021 10:11:09 +0100 |
Version 2 of ("vhost-user: Check for iotlb callback in iotlb_miss") [1].
Starting a new series, since the title does not reflect the changes anymore.
Thanks!
[1] 20210127204449.745365-1-eperezma@redhat.com/">https://patchew.org/QEMU/20210127204449.745365-1-eperezma@redhat.com/
On Fri, Jan 29, 2021 at 10:08 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Not checking this can lead to invalid dev->vdev member access in
> vhost_device_iotlb_miss if backend issue an iotlb message in a bad
> timing, either maliciously or by a bug.
>
> Reproduced rebooting a guest with testpmd in txonly forward mode.
> #0 0x0000559ffff94394 in vhost_device_iotlb_miss (
> dev=dev@entry=0x55a0012f6680, iova=10245279744, write=1)
> at ../hw/virtio/vhost.c:1013
> #1 0x0000559ffff9ac31 in vhost_backend_handle_iotlb_msg (
> imsg=0x7ffddcfd32c0, dev=0x55a0012f6680)
> at ../hw/virtio/vhost-backend.c:411
> #2 vhost_backend_handle_iotlb_msg (dev=dev@entry=0x55a0012f6680,
> imsg=imsg@entry=0x7ffddcfd32c0)
> at ../hw/virtio/vhost-backend.c:404
> #3 0x0000559fffeded7b in slave_read (opaque=0x55a0012f6680)
> at ../hw/virtio/vhost-user.c:1464
> #4 0x000055a0000c541b in aio_dispatch_handler (
> ctx=ctx@entry=0x55a0010a2120, node=0x55a0012d9e00)
> at ../util/aio-posix.c:329
>
> Fixes: 6dcdd06e3b ("spec/vhost-user spec: Add IOMMU support")
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
> hw/virtio/vhost-backend.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 222bbcc62d..31b33bde37 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -406,6 +406,11 @@ int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
> {
> int ret = 0;
>
> + if (unlikely(!dev->vdev)) {
> + error_report("Unexpected IOTLB message when virtio device is
> stopped");
> + return -EINVAL;
> + }
> +
> switch (imsg->type) {
> case VHOST_IOTLB_MISS:
> ret = vhost_device_iotlb_miss(dev, imsg->iova,
> --
> 2.27.0
>
>