can: grcan: 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: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/grcan.c

@@ -1216,11 +1216,12 @@ static int grcan_receive(struct net_device *dev, int budget)
 				cf->data[i] = (u8)(slot[j] >> shift);
 			}
 		}
-		netif_receive_skb(skb);
 
 		/* Update statistics and read pointer */
 		stats->rx_packets++;
 		stats->rx_bytes += cf->can_dlc;
+		netif_receive_skb(skb);
+
 		rd = grcan_ring_add(rd, GRCAN_MSG_SIZE, dma->rx.size);
 	}