netdev - [PATCH net] gro_cells: Avoid packet re-ordering for cloned skbs

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Message-Id: <20250109142724.29228-1-tbogendoerfer@suse.de>
Date: Thu,  9 Jan 2025 15:27:24 +0100
From: Thomas Bogendoerfer <tbogendoerfer@...e.de>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net] gro_cells: Avoid packet re-ordering for cloned skbs

gro_cells_receive() passes a cloned skb directly up the stack and
could cause re-ordering against segments still in GRO. To avoid
this copy the skb and let GRO do it's work.

Fixes: c9e6bc644e55 ("net: add gro_cells infrastructure")
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@...e.de>
---
 net/core/gro_cells.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index ff8e5b64bf6b..2f8d688f9d82 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c
@@ -20,11 +20,20 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 	if (unlikely(!(dev->flags & IFF_UP)))
 		goto drop;
 
-	if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) {
+	if (!gcells->cells || netif_elide_gro(dev)) {
+netif_rx:
 		res = netif_rx(skb);
 		goto unlock;
 	}
+	if (skb_cloned(skb)) {
+		struct sk_buff *n;
 
+		n = skb_copy(skb, GFP_KERNEL);
+		if (!n)
+			goto netif_rx;
+		kfree_skb(skb);
+		skb = n;
+	}
 	cell = this_cpu_ptr(gcells->cells);
 
 	if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
-- 
2.35.3