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From:   Thomas Bogendoerfer <tbogendoerfer@suse.de>
To:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH net] net: mellanox: mlxbf_gige: Fix skb_panic splat under memory pressure
Date:   Mon, 22 May 2023 21:07:13 +0200
Message-Id: <20230522190713.82417-1-tbogendoerfer@suse.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Do skp_put() after a new skb has been successfully allocated otherwise
the reused skb leads to skp_panics or incorrect packet sizes.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 .../ethernet/mellanox/mlxbf_gige/mlxbf_gige_rx.c    | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_rx.c b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_rx.c
index afa3b92a6905..2c132849a76d 100644
--- a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_rx.c
+++ b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_rx.c
@@ -245,18 +245,19 @@ static bool mlxbf_gige_rx_packet(struct mlxbf_gige *priv, int *rx_pkts)
 
 		skb = priv->rx_skb[rx_pi_rem];
 
-		skb_put(skb, datalen);
-
-		skb->ip_summed = CHECKSUM_NONE; /* device did not checksum packet */
-
-		skb->protocol = eth_type_trans(skb, netdev);
-
 		/* Alloc another RX SKB for this same index */
 		rx_skb = mlxbf_gige_alloc_skb(priv, MLXBF_GIGE_DEFAULT_BUF_SZ,
 					      &rx_buf_dma, DMA_FROM_DEVICE);
 		if (!rx_skb)
 			return false;
 		priv->rx_skb[rx_pi_rem] = rx_skb;
+
+		skb_put(skb, datalen);
+
+		skb->ip_summed = CHECKSUM_NONE; /* device did not checksum packet */
+
+		skb->protocol = eth_type_trans(skb, netdev);
+
 		dma_unmap_single(priv->dev, *rx_wqe_addr,
 				 MLXBF_GIGE_DEFAULT_BUF_SZ, DMA_FROM_DEVICE);
 		*rx_wqe_addr = rx_buf_dma;
-- 
2.35.3