netdev - [PATCH 10/12] can: ems_usb: don't touch skb after netif

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Date:	Wed, 15 Jul 2015 09:09:47 +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>,
	Gerhard Uttenthaler <uttenthaler@...-wuensche.com>
Subject: [PATCH 10/12] can: ems_usb: don't touch skb after 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.

Cc: Gerhard Uttenthaler <uttenthaler@...-wuensche.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/usb/ems_usb.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c
index 866bac0ae7e9..2d390384ef3b 100644
--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -324,10 +324,9 @@ static void ems_usb_rx_can_msg(struct ems_usb *dev, struct ems_cpc_msg *msg)
 			cf->data[i] = msg->msg.can_msg.msg[i];
 	}
 
-	netif_rx(skb);
-
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
+	netif_rx(skb);
 }
 
 static void ems_usb_rx_err(struct ems_usb *dev, struct ems_cpc_msg *msg)
@@ -400,10 +399,9 @@ static void ems_usb_rx_err(struct ems_usb *dev, struct ems_cpc_msg *msg)
 		stats->rx_errors++;
 	}
 
-	netif_rx(skb);
-
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
+	netif_rx(skb);
 }
 
 /*
-- 
2.1.4

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