[patch V2 04/21] can: c_can: Do not access skb after net_receive_skb()

[Thomas Gleixner <tglx@linutronix.de>]

[-- Attachment #1: can-c_can-do-not-access-skb-after-netif_rx.patch --]
[-- Type: text/plain, Size: 1384 bytes --]

There is no guarantee that the skb is in the same state after calling
net_receive_skb(). 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.

The whole can subsystem is full of this. Copy and paste ....

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 drivers/net/can/c_can/c_can.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6/drivers/net/can/c_can/c_can.c
===================================================================
--- linux-2.6.orig/drivers/net/can/c_can/c_can.c
+++ linux-2.6/drivers/net/can/c_can/c_can.c
@@ -429,10 +429,10 @@ static int c_can_read_msg_object(struct
 		}
 	}
 
-	netif_receive_skb(skb);
-
 	stats->rx_packets++;
 	stats->rx_bytes += frame->can_dlc;
+
+	netif_receive_skb(skb);
 	return 0;
 }
 
@@ -960,9 +960,9 @@ static int c_can_handle_state_change(str
 		break;
 	}
 
-	netif_receive_skb(skb);
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
 
 	return 1;
 }
@@ -1033,10 +1033,9 @@ static int c_can_handle_bus_err(struct n
 	/* set a `lec` value so that we can check for updates later */
 	priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED);
 
-	netif_receive_skb(skb);
 	stats->rx_packets++;
 	stats->rx_bytes += cf->can_dlc;
-
+	netif_receive_skb(skb);
 	return 1;
 }