netdev - [PATCH 01/12] can: at91_can: don't touch skb after netif_receive_skb()/netif

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Date:	Wed, 15 Jul 2015 09:09:38 +0200
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	netdev@...r.kernel.org
Cc:	davem@...emloft.net, linux-can@...r.kernel.org,
	kernel@...gutronix.de, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 01/12] can: at91_can: don't touch skb after netif_receive_skb()/netif_rx()

There is no guarantee that the skb is in the same state after calling
net_receive_skb() or netif_rx(). It might be freed or reused. Not really
harmful as its a read access, except you turn on the proper debugging options
which catch a use after free.

Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/at91_can.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index f4e40aa4d2a2..945c0955a967 100644
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -577,10 +577,10 @@ static void at91_rx_overflow_err(struct net_device *dev)
 
 	cf->can_id |= CAN_ERR_CRTL;
 	cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
-	netif_receive_skb(skb);
 
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
 }
 
 /**
@@ -642,10 +642,10 @@ static void at91_read_msg(struct net_device *dev, unsigned int mb)
 	}
 
 	at91_read_mb(dev, mb, cf);
-	netif_receive_skb(skb);
 
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
 
 	can_led_event(dev, CAN_LED_EVENT_RX);
 }
@@ -802,10 +802,10 @@ static int at91_poll_err(struct net_device *dev, int quota, u32 reg_sr)
 		return 0;
 
 	at91_poll_err_frame(dev, cf, reg_sr);
-	netif_receive_skb(skb);
 
 	dev->stats.rx_packets++;
 	dev->stats.rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
 
 	return 1;
 }
@@ -1067,10 +1067,10 @@ static void at91_irq_err(struct net_device *dev)
 		return;
 
 	at91_irq_err_state(dev, cf, new_state);
-	netif_rx(skb);
 
 	dev->stats.rx_packets++;
 	dev->stats.rx_bytes += cf->can_dlc;
+	netif_rx(skb);
 
 	priv->can.state = new_state;
 }
-- 
2.1.4

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