[PATCH 4.19 30/74] can: pch_can: pch_can_rx_normal: fix use after free

[Greg Kroah-Hartman]

From: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>

commit 94cddf1e9227a171b27292509d59691819c458db upstream.

After calling netif_receive_skb(skb), dereferencing skb is unsafe.
Especially, the can_frame cf which aliases skb memory is dereferenced
just after the call netif_receive_skb(skb).

Reordering the lines solves the issue.

Fixes: b21d18b51b31 ("can: Topcliff: Add PCH_CAN driver.")
Link: https://lore.kernel.org/all/20211123111654.621610-1-mailhol.vincent@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/can/pch_can.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/can/pch_can.c
+++ b/drivers/net/can/pch_can.c
@@ -703,11 +703,11 @@ static int pch_can_rx_normal(struct net_
 			cf->data[i + 1] = data_reg >> 8;
 		}
 
-		netif_receive_skb(skb);
 		rcv_pkts++;
 		stats->rx_packets++;
 		quota--;
 		stats->rx_bytes += cf->can_dlc;
+		netif_receive_skb(skb);
 
 		pch_fifo_thresh(priv, obj_num);
 		obj_num++;