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| author | Felipe Franciosi | 2020-10-28 14:47:03 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin | 2020-10-30 11:48:53 +0100 |
| commit | d68cdae30eef62dde61c8b8467a96c01c8f80270 (patch) | |
| tree | dc6637d3e57451ec22727a1ff391def14f8c290d /hw | |
| parent | vhost-blk: set features before setting inflight feature (diff) | |
| download | qemu-d68cdae30eef62dde61c8b8467a96c01c8f80270.tar.gz qemu-d68cdae30eef62dde61c8b8467a96c01c8f80270.tar.xz qemu-d68cdae30eef62dde61c8b8467a96c01c8f80270.zip | |
virtio: skip guest index check on device load
QEMU must be careful when loading device state off migration streams to
prevent a malicious source from exploiting the emulator. Overdoing these
checks has the side effect of allowing a guest to "pin itself" in cloud
environments by messing with state which is entirely in its control.
Similarly to what f3081539 achieved in usb_device_post_load(), this
commit removes such a check from virtio_load(). Worth noting, the result
of a load without this check is the same as if a guest enables a VQ with
invalid indexes to begin with. That is, the virtual device is set in a
broken state (by the datapath handler) and must be reset.
Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
Message-Id: <20201028134643.110698-1-felipe@nutanix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw')
| -rw-r--r-- | hw/virtio/virtio.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 6f8f865aff..ceb58fda6c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -17,6 +17,7 @@ #include "trace.h" #include "exec/address-spaces.h" #include "qemu/error-report.h" +#include "qemu/log.h" #include "qemu/main-loop.h" #include "qemu/module.h" #include "hw/virtio/virtio.h" @@ -3160,12 +3161,12 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id) nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx; /* Check it isn't doing strange things with descriptor numbers. */ if (nheads > vdev->vq[i].vring.num) { - error_report("VQ %d size 0x%x Guest index 0x%x " - "inconsistent with Host index 0x%x: delta 0x%x", - i, vdev->vq[i].vring.num, - vring_avail_idx(&vdev->vq[i]), - vdev->vq[i].last_avail_idx, nheads); - return -1; + qemu_log_mask(LOG_GUEST_ERROR, + "VQ %d size 0x%x Guest index 0x%x " + "inconsistent with Host index 0x%x: delta 0x%x", + i, vdev->vq[i].vring.num, + vring_avail_idx(&vdev->vq[i]), + vdev->vq[i].last_avail_idx, nheads); } vdev->vq[i].used_idx = vring_used_idx(&vdev->vq[i]); vdev->vq[i].shadow_avail_idx = vring_avail_idx(&vdev->vq[i]); |