linux-kernel - Re: [PATCH net V2] virtio-net: zero unused hash fields

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Message-ID: <1761105287.0200958-1-xuanzhuo@linux.alibaba.com>
Date: Wed, 22 Oct 2025 11:54:47 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: Jason Wang <jasowang@...hat.com>
Cc: netdev@...r.kernel.org,
 stable@...r.kernel.org,
 mst@...hat.com,
 jasowang@...hat.com,
 eperezma@...hat.com,
 pabeni@...hat.com,
 virtualization@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net V2] virtio-net: zero unused hash fields

On Wed, 22 Oct 2025 11:44:21 +0800, Jason Wang <jasowang@...hat.com> wrote:
> When GSO tunnel is negotiated virtio_net_hdr_tnl_from_skb() tries to
> initialize the tunnel metadata but forget to zero unused rxhash
> fields. This may leak information to another side. Fixing this by
> zeroing the unused hash fields.

Reviewed-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>

>
> Acked-by: Michael S. Tsirkin <mst@...hat.com>
> Fixes: a2fb4bc4e2a6a ("net: implement virtio helpers to handle UDP GSO tunneling")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Jason Wang <jasowang@...hat.com>
> ---
>  include/linux/virtio_net.h | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 20e0584db1dd..4d1780848d0e 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -401,6 +401,10 @@ virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb,
>  	if (!tnl_hdr_negotiated)
>  		return -EINVAL;
>
> +        vhdr->hash_hdr.hash_value = 0;
> +        vhdr->hash_hdr.hash_report = 0;
> +        vhdr->hash_hdr.padding = 0;
> +
>  	/* Let the basic parsing deal with plain GSO features. */
>  	skb_shinfo(skb)->gso_type &= ~tnl_gso_type;
>  	ret = virtio_net_hdr_from_skb(skb, hdr, true, false, vlan_hlen);
> --
> 2.42.0
>