Commit 5177373c authored by Bui Quang Minh's avatar Bui Quang Minh Committed by Paolo Abeni
Browse files

virtio-net: xsk: rx: fix the frame's length check 



When calling buf_to_xdp, the len argument is the frame data's length
without virtio header's length (vi->hdr_len). We check that len with

	xsk_pool_get_rx_frame_size() + vi->hdr_len

to ensure the provided len does not larger than the allocated chunk
size. The additional vi->hdr_len is because in virtnet_add_recvbuf_xsk,
we use part of XDP_PACKET_HEADROOM for virtio header and ask the vhost
to start placing data from

	hard_start + XDP_PACKET_HEADROOM - vi->hdr_len
not
	hard_start + XDP_PACKET_HEADROOM

But the first buffer has virtio_header, so the maximum frame's length in
the first buffer can only be

	xsk_pool_get_rx_frame_size()
not
	xsk_pool_get_rx_frame_size() + vi->hdr_len

like in the current check.

This commit adds an additional argument to buf_to_xdp differentiate
between the first buffer and other ones to correctly calculate the maximum
frame's length.

Cc: stable@vger.kernel.org
Reviewed-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Fixes: a4e7ba70 ("virtio_net: xsk: rx: support recv small mode")
Signed-off-by: default avatarBui Quang Minh <minhquangbui99@gmail.com>
Link: https://patch.msgid.link/20250630151315.86722-2-minhquangbui99@gmail.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent c9cbbe7a

drivers/net/virtio_net.c

+18 −4
Original line number Diff line number Diff line
@@ -1147,15 +1147,29 @@ static void check_sq_full_and_disable(struct virtnet_info *vi, 
	}

}



/* Note that @len is the length of received data without virtio header */

static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi,

				   struct receive_queue *rq, void *buf, u32 len)

				   struct receive_queue *rq, void *buf,

				   u32 len, bool first_buf)

{

	struct xdp_buff *xdp;

	u32 bufsize;



	xdp = (struct xdp_buff *)buf;



	bufsize = xsk_pool_get_rx_frame_size(rq->xsk_pool) + vi->hdr_len;

	/* In virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for

	 * virtio header and ask the vhost to fill data from

	 *         hard_start + XDP_PACKET_HEADROOM - vi->hdr_len

	 * The first buffer has virtio header so the remaining region for frame

	 * data is

	 *         xsk_pool_get_rx_frame_size()

	 * While other buffers than the first one do not have virtio header, so

	 * the maximum frame data's length can be

	 *         xsk_pool_get_rx_frame_size() + vi->hdr_len

	 */

	bufsize = xsk_pool_get_rx_frame_size(rq->xsk_pool);

	if (!first_buf)

		bufsize += vi->hdr_len;



	if (unlikely(len > bufsize)) {

		pr_debug("%s: rx error: len %u exceeds truesize %u\n",
@@ -1280,7 +1294,7 @@ static int xsk_append_merge_buffer(struct virtnet_info *vi, 


		u64_stats_add(&stats->bytes, len);



		xdp = buf_to_xdp(vi, rq, buf, len);

		xdp = buf_to_xdp(vi, rq, buf, len, false);

		if (!xdp)

			goto err;
@@ -1378,7 +1392,7 @@ static void virtnet_receive_xsk_buf(struct virtnet_info *vi, struct receive_queu 


	u64_stats_add(&stats->bytes, len);



	xdp = buf_to_xdp(vi, rq, buf, len);

	xdp = buf_to_xdp(vi, rq, buf, len, true);

	if (!xdp)

		return;