The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 94cddf1e9227a171b27292509d59691819c458db Mon Sep 17 00:00:00 2001

From: Vincent Mailhol mailhol.vincent@wanadoo.fr Date: Tue, 23 Nov 2021 20:16:54 +0900 Subject: [PATCH] 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.... 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 92a54a5fd4c5..964c8a09226a 100644 --- 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++;