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

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Message-ID: <20251022034421.70244-1-jasowang@redhat.com>
Date: Wed, 22 Oct 2025 11:44:21 +0800
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com,
	jasowang@...hat.com,
	xuanzhuo@...ux.alibaba.com,
	eperezma@...hat.com,
	pabeni@...hat.com,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: netdev@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH net V2] virtio-net: zero unused hash fields

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@...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