Re: [Qemu-devel] [PATCH v2] virtio-rng: Add human-readable error message for negative max-bytes parameter

[Markus Armbruster]

John Snow <address@hidden> writes:

> If a negative integer is used for the max_bytes parameter, QEMU currently
> calls abort() and leaves behind a core dump. This patch adds a simple
> error message to make the reason for the termination clearer.
>
> Signed-off-by: John Snow <address@hidden>
> ---
> v2: Changed 0L constant to (uint64_t)0 constant to match PRId64 format code
>     on both 32bit and 64bit systems. Tested via -m32 flag.
>
>  hw/virtio/virtio-rng.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 1356aca..64c7d23 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -181,7 +181,11 @@ static void virtio_rng_device_realize(DeviceState *dev, 
> Error **errp)
>  
>      vrng->vq = virtio_add_queue(vdev, 8, handle_input);
>  
> -    assert(vrng->conf.max_bytes <= INT64_MAX);
> +    if (vrng->conf.max_bytes > INT64_MAX) {
> +        error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE, "virtio-rng",
> +                  "max_bytes", vrng->conf.max_bytes, (uint64_t)0, INT64_MAX);
> +        return;
> +    }
>      vrng->quota_remaining = vrng->conf.max_bytes;
>  
>      vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,

Elsewhere in this function, we use

        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "period",
                  "a positive number");

Existing uses of QERR_PROPERTY_VALUE_OUT_OF_RANGE are all for intervals
with small bounds.