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

From: Jason Wang
Date: Tue May 25 2021 - 02:23:41 EST



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@xxxxxxxxxxxxx>


Acked-by: Jason Wang <jasowang@xxxxxxxxxx>


---
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);