Multiple heap-based buffer overflows in the virtio-blk driver (hw/virtio-blk.c) in qemu-kvm 0.14.0 allow local guest users to cause a denial of service (guest crash) and possibly gain privileges via a (1) write request to the virtio_blk_handle_write function or (2) read request to the virtio_blk_handle_read function that is not properly aligned.