can: pch_can: pch_can_rx_normal: fix use after free

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@wanadoo.fr
Cc: stable@vger.kernel.org
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
index 92a54a5fd4c502c3238f500e9bf39b44b44582a6..964c8a09226a9fc1af3de261948d62638ff9f48e 100644 (file)
--- a/drivers/net/can/pch_can.c
+++ b/drivers/net/can/pch_can.c
@@ -692,11 +692,11 @@ static int pch_can_rx_normal(struct net_device *ndev, u32 obj_num, int quota)
                        cf->data[i + 1] = data_reg >> 8;
                }
 
-               netif_receive_skb(skb);
                rcv_pkts++;
                stats->rx_packets++;
                quota--;
                stats->rx_bytes += cf->len;
+               netif_receive_skb(skb);
 
                pch_fifo_thresh(priv, obj_num);
                obj_num++;