linux-kernel - Re: [PATCH] virtio_console: Assure used length from device is limited

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Message-ID: <007b4e26-8ea1-ac22-fd77-e54b7417351b@redhat.com>
Date:   Tue, 25 May 2021 14:23:19 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>, amit@...nel.org,
        mst@...hat.com
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] virtio_console: Assure used length from device is limited


在 2021/5/25 下午12:53, Xie Yongji 写道:
> The buf->len might come from an untrusted device. This
> ensures the value would not exceed the size of the buffer
> to avoid data corruption or loss.
>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>


Acked-by: Jason Wang <jasowang@...hat.com>


> ---
>   drivers/char/virtio_console.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 1c40ca6d76ba..598863e6daf8 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -475,7 +475,7 @@ static struct port_buffer *get_inbuf(struct port *port)
>   
>   	buf = virtqueue_get_buf(port->in_vq, &len);
>   	if (buf) {
> -		buf->len = len;
> +		buf->len = min(len, buf->size);
>   		buf->offset = 0;
>   		port->stats.bytes_received += len;
>   	}
> @@ -1709,7 +1709,7 @@ static void control_work_handler(struct work_struct *work)
>   	while ((buf = virtqueue_get_buf(vq, &len))) {
>   		spin_unlock(&portdev->c_ivq_lock);
>   
> -		buf->len = len;
> +		buf->len = min(len, buf->size);
>   		buf->offset = 0;
>   
>   		handle_control_message(vq->vdev, portdev, buf);