[PATCH 7.1 062/228] gve: fix zero-length skb frag with header-split

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jordan Rhee <[email protected]>

commit 6bf14575c65569dcded90ef78afb8a6d57323f04 upstream.

When header split is enabled and a header-only packet is
received such as a pure TCP ACK, GVE will indicate an
RX SKB with a zero-length fragment. If this SKB is then
hairpinned and sent back out, the GVE TX path will emit
a zero-length descriptor. Hardware considers this
an illegal descriptor and stops the queue, causing a
TX timeout and interface reset.

Fix it by not adding the zero-length skb frag.

Cc: [email protected]
Fixes: 5e37d8254e7f ("gve: Add header split data path")
Suggested-by: Praveen Kaligineedi <[email protected]>
Co-developed-by: Ziwei Xiao <[email protected]>
Signed-off-by: Ziwei Xiao <[email protected]>
Signed-off-by: Jordan Rhee <[email protected]>
Signed-off-by: Harshitha Ramamurthy <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/net/ethernet/google/gve/gve_rx_dqo.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -886,6 +886,11 @@ static int gve_rx_dqo(struct napi_struct
 		rx->rx_hsplit_unsplit_pkt += unsplit;
 		rx->rx_hsplit_bytes += hdr_len;
 		u64_stats_update_end(&rx->statss);
+
+		if (!buf_len) {
+			gve_free_buffer(rx, buf_state);
+			return 0;
+		}
 	} else if (!rx->ctx.skb_head && rx->dqo.page_pool &&
 		   netmem_is_net_iov(buf_state->page_info.netmem)) {
 		/* when header split is disabled, the header went to the packet