[PATCH net] virtio_net: fix header access in big_packets mode
From: Wen Xin <hidden>
Date: 2025-10-16 23:33:19
Also in:
virtualization
Subsystem:
networking drivers, the rest, virtio net driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang
In Linux virtio-net driver's (drivers/net/virtio_net.c) big packets mode (vi->big_packets && vi->mergeable_rx_bufs), the buf pointer passed to receive_buf() is a struct page pointer, not a buffer pointer. The current code incorrectly casts this page pointer directly as a virtio_net_common_hdr, causing it to read flags from the page struct memory instead of the actual packet data. Signed-off-by: Wen Xin <redacted> --- drivers/net/virtio_net.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7646ddd9bef7..c10f5585bc88 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -2566,7 +2566,13 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, * 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->big_packets && !vi->mergeable_rx_bufs) { + struct virtio_net_common_hdr *hdr = page_address((struct page *)buf); + + flags = hdr->hdr.flags; + } else { + flags = ((struct virtio_net_common_hdr *)buf)->hdr.flags; + } if (vi->mergeable_rx_bufs) skb = receive_mergeable(dev, vi, rq, buf, ctx, len, xdp_xmit,
--
2.39.5 (Apple Git-154)