[PATCH 5.15 024/171] can: pch_can: pch_can_rx_normal: fix use after free

Greg Kroah-Hartman
2021-12-13T09:59:59Z

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
@@ -692,11 +692,11 @@ 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->len;
+ netif_receive_skb(skb);

pch_fifo_thresh(priv, obj_num);
obj_num++;