On 2020/10/28 下午9:47, Felipe Franciosi wrote:
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 <fel...@nutanix.com> --- v2: Keep the check around for logging. hw/virtio/virtio.c | 13 +++++++------ 1 file 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]);
Acked-by: Jason Wang <jasow...@redhat.com>