[PATCH 5.4 51/86] can: peak_usb: fix use after free bugs

Greg Kroah-Hartman
2021-01-26T08:52:20Z

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

[ 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>
---
drivers/net/can/usb/peak_usb/pcan_usb_fd.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

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 dee3e689b54da..96bbdef672bc9 100644
--- 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;
}

--
2.27.0