[PATCH net v3 1/2] virtio-net: xsk: rx: fix the frame's length check
From: Bui Quang Minh <hidden>
Date: 2025-06-30 15:13:43
Also in:
bpf, lkml, stable, 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
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: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Fixes: a4e7ba702701 ("virtio_net: xsk: rx: support recv small mode")
Signed-off-by: Bui Quang Minh <redacted>
---
drivers/net/virtio_net.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e53ba600605a..1eb237cd5d0b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -1127,15 +1127,29 @@ 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",
@@ -1260,7 +1274,7 @@ 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;
@@ -1358,7 +1372,7 @@ 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;
--
2.43.0