netdev - [PATCH net v3 1/3] virtio-net: fix incorrect flags recording in big mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251024074130.65580-2-xuanzhuo@linux.alibaba.com>
Date: Fri, 24 Oct 2025 15:41:28 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: netdev@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Jiri Pirko <jiri@...nulli.us>,
	Alvaro Karsz <alvaro.karsz@...id-run.com>,
	Heng Qi <hengqi@...ux.alibaba.com>,
	virtualization@...ts.linux.dev
Subject: [PATCH net v3 1/3] virtio-net: fix incorrect flags recording in big mode

The purpose of commit 703eec1b2422 ("virtio_net: fixing XDP for fully
checksummed packets handling") is to record the flags in advance, as
their value may be overwritten in the XDP case. However, the flags
recorded under big mode are incorrect, because in big mode, the passed
buf does not point to the rx buffer, but rather to the page of the
submitted buffer. This commit fixes this issue.

For the small mode, the commit c11a49d58ad2 ("virtio_net: Fix mismatched
buf address when unmapping for small packets") fixed it.

Fixes: 703eec1b2422 ("virtio_net: fixing XDP for fully checksummed packets handling")
Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Acked-by: Jason Wang <jasowang@...hat.com>
---
 drivers/net/virtio_net.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8e8a179aaa49..59f116b609f6 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2625,22 +2625,28 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 		return;
 	}
 
-	/* 1. Save the flags early, as the XDP program might overwrite them.
+	/* About the flags below:
+	 * 1. Save the flags early, as the XDP program might overwrite them.
 	 * These flags ensure packets marked as VIRTIO_NET_HDR_F_DATA_VALID
 	 * stay valid after XDP processing.
 	 * 2. XDP doesn't work with partially checksummed packets (refer to
 	 * virtnet_xdp_set()), so packets marked as
 	 * VIRTIO_NET_HDR_F_NEEDS_CSUM get dropped during XDP processing.
 	 */
-	flags = ((struct virtio_net_common_hdr *)buf)->hdr.flags;
 
-	if (vi->mergeable_rx_bufs)
+	if (vi->mergeable_rx_bufs) {
+		flags = ((struct virtio_net_common_hdr *)buf)->hdr.flags;
 		skb = receive_mergeable(dev, vi, rq, buf, ctx, len, xdp_xmit,
 					stats);
-	else if (vi->big_packets)
+	} else if (vi->big_packets) {
+		void *p = page_address((struct page *)buf);
+
+		flags = ((struct virtio_net_common_hdr *)p)->hdr.flags;
 		skb = receive_big(dev, vi, rq, buf, len, stats);
-	else
+	} else {
+		flags = ((struct virtio_net_common_hdr *)buf)->hdr.flags;
 		skb = receive_small(dev, vi, rq, buf, ctx, len, xdp_xmit, stats);
+	}
 
 	if (unlikely(!skb))
 		return;
-- 
2.32.0.3.g01195cf9f