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

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

[Jason Wang]

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.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: a2fb4bc4e2a6a ("net: implement virtio helpers to handle UDP GSO tunneling")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Wang <jasowang@redhat.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

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

[Xuan Zhuo]

On Wed, 22 Oct 2025 11:44:21 +0800, Jason Wang <jasowang@redhat.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@linux.alibaba.com>

>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Fixes: a2fb4bc4e2a6a ("net: implement virtio helpers to handle UDP GSO tunneling")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Jason Wang <jasowang@redhat.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
>

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

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 22 Oct 2025 11:44:21 +0800 you 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.
> 
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Fixes: a2fb4bc4e2a6a ("net: implement virtio helpers to handle UDP GSO tunneling")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> 
> [...]

Here is the summary with links:
  - [net,V2] virtio-net: zero unused hash fields
    https://git.kernel.org/netdev/net/c/b2284768c6b3

You are awesome, thank you!
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