Add hash_key_length check in virtnet_probe() to avoid possible out of
bound errors when setting/reading the hash key.

Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.")
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 75c1ff4efd13..acc3e5dc112e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -6451,6 +6451,12 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (vi->has_rss || vi->has_rss_hash_report) {
 		vi->rss_key_size =
 			virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
+		if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
+			dev_err(&vdev->dev, "rss_max_key_size=%u exceeds the limit %u.\n",
+				vi->rss_key_size, VIRTIO_NET_RSS_MAX_KEY_SIZE);
+			err = -EINVAL;
+			goto free;
+		}
 
 		vi->rss_hash_types_supported =
 		    virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));
-- 
2.32.0.3.g01195cf9f

On Mon, Nov 04, 2024 at 04:57:04PM +0800, Philo Lu wrote:
> Add hash_key_length check in virtnet_probe() to avoid possible out of
> bound errors when setting/reading the hash key.
> 
> Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.")
> Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  drivers/net/virtio_net.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 75c1ff4efd13..acc3e5dc112e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -6451,6 +6451,12 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (vi->has_rss || vi->has_rss_hash_report) {
>  		vi->rss_key_size =
>  			virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
> +		if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
> +			dev_err(&vdev->dev, "rss_max_key_size=%u exceeds the limit %u.\n",
> +				vi->rss_key_size, VIRTIO_NET_RSS_MAX_KEY_SIZE);
> +			err = -EINVAL;
> +			goto free;
> +		}

I agree that an out of bounds error could occur and a check here
is needed.

I have no idea if returning -EINVAL from probe is the correct
solution (vs say using min()) as I am just a casual observer of
virtio_net and not a maintainer.

Acked-by: Joe Damato <jdamato@fastly.com>