Re: [Qemu-devel] [PATCH 1/6] virtio: introduce virtio_map

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Oct 27, 2015 at 10:47:56AM +0200, Michael S. Tsirkin wrote:
> +    for (i = 0; i < *num_sg; i++) {
>          len = sg[i].iov_len;
>          sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write);
> -        if (sg[i].iov_base == NULL || len != sg[i].iov_len) {
> +        if (!sg[i].iov_base) {
>              error_report("virtio: error trying to map MMIO memory");
>              exit(1);
>          }
> +        if (len == sg[i].iov_len) {
> +            continue;
> +        }
> +        if (*num_sg >= max_size) {
> +            error_report("virtio: memory split makes iovec too large");
> +            exit(1);
> +        }
> +        memcpy(sg + i + 1, sg + i, sizeof(*sg) * (*num_sg - i));
> +        memcpy(addr + i + 1, addr + i, sizeof(*addr) * (*num_sg - i));

These should be memmove() since memcpy() arguments are not allowed to overlap.