From: Greg Kurz <groug@xxxxxxxx> commit 71878fa46c7e3b40fa7b3f1b6e4ba3f92f1ac359 upstream. The open-coded computation of the used size doesn't take the event into account when the VIRTIO_RING_F_EVENT_IDX feature is present. Fix that by using vhost_get_used_size(). Fixes: 8ea8cf89e19a ("vhost: support event index") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kurz <groug@xxxxxxxx> Link: https://lore.kernel.org/r/160171932300.284610.11846106312938909461.stgit@xxxxxxxxx Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/vhost/vhost.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1545,8 +1545,7 @@ static long vhost_vring_set_addr(struct /* Also validate log access for used ring if enabled. */ if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && !log_access_ok(vq->log_base, a.log_guest_addr, - sizeof *vq->used + - vq->num * sizeof *vq->used->ring)) + vhost_get_used_size(vq, vq->num))) return -EINVAL; }