can: peak_usb: fix use after free bugs

[ Upstream commit 50aca891d7a554db0901b245167cd653d73aaa71 ]

After calling peak_usb_netif_rx_ni(skb), dereferencing skb is unsafe.
Especially, the can_frame cf which aliases skb memory is accessed
after the peak_usb_netif_rx_ni().

Reordering the lines solves the issue.

Fixes: 0a25e1f4f185 ("can: peak_usb: add support for PEAK new CANFD USB adapters")
Link: https://lore.kernel.org/r/20210120114137.200019-4-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
index d29d205..d565922 100644 (file)
--- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
@@ -512,11 +512,11 @@ static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
        else
                memcpy(cfd->data, rm->d, cfd->len);
 
-       peak_usb_netif_rx(skb, &usb_if->time_ref, le32_to_cpu(rm->ts_low));
-
        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += cfd->len;
 
+       peak_usb_netif_rx(skb, &usb_if->time_ref, le32_to_cpu(rm->ts_low));
+
        return 0;
 }
 
@@ -578,11 +578,11 @@ static int pcan_usb_fd_decode_status(struct pcan_usb_fd_if *usb_if,
        if (!skb)
                return -ENOMEM;
 
-       peak_usb_netif_rx(skb, &usb_if->time_ref, le32_to_cpu(sm->ts_low));
-
        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += cf->can_dlc;
 
+       peak_usb_netif_rx(skb, &usb_if->time_ref, le32_to_cpu(sm->ts_low));
+
        return 0;
 }