netdev - [net V2 09/15] net/mlx5e: Avoid referencing skb after free-ing in drop path of mlx5e_sq_xmit

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Date: Tue, 14 Nov 2023 13:58:40 -0800
From: Saeed Mahameed <saeed@...nel.org>
To: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>
Cc: Saeed Mahameed <saeedm@...dia.com>,
	netdev@...r.kernel.org,
	Tariq Toukan <tariqt@...dia.com>,
	Rahul Rameshbabu <rrameshbabu@...dia.com>
Subject: [net V2 09/15] net/mlx5e: Avoid referencing skb after free-ing in drop path of mlx5e_sq_xmit_wqe

From: Rahul Rameshbabu <rrameshbabu@...dia.com>

When SQ is a port timestamping SQ for PTP, do not access tx flags of skb
after free-ing the skb. Free the skb only after all references that depend
on it have been handled in the dropped WQE path.

Fixes: 3178308ad4ca ("net/mlx5e: Make tx_port_ts logic resilient to out-of-order CQEs")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@...dia.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
index d41435c22ce5..19f2c25b05a0 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
@@ -494,10 +494,10 @@ mlx5e_sq_xmit_wqe(struct mlx5e_txqsq *sq, struct sk_buff *skb,
 
 err_drop:
 	stats->dropped++;
-	dev_kfree_skb_any(skb);
 	if (unlikely(sq->ptpsq && (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)))
 		mlx5e_ptp_metadata_fifo_push(&sq->ptpsq->metadata_freelist,
 					     be32_to_cpu(eseg->flow_table_metadata));
+	dev_kfree_skb_any(skb);
 	mlx5e_tx_flush(sq);
 }
 
-- 
2.41.0