[PATCH 5.17 0071/1126] can: m_can: m_can_tx_handler(): fix use after free of skb

Greg Kroah-Hartman
2022-04-05T08:01:21Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

commit 2e8e79c416aae1de224c0f1860f2e3350fa171f8 upstream.

can_put_echo_skb() will clone skb then free the skb. Move the
can_put_echo_skb() for the m_can version 3.0.x directly before the
start of the xmit in hardware, similar to the 3.1.x branch.

Fixes: 80646733f11c ("can: m_can: update to support CAN FD features")
Link: https://lore.kernel.org/all/20220317081305.739554-1-mkl@pengutronix.de
Cc: stable@vger.kernel.org
Reported-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/can/m_can/m_can.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1637,8 +1637,6 @@ static netdev_tx_t m_can_tx_handler(stru
if (err)
goto out_fail;

- can_put_echo_skb(skb, dev, 0, 0);
-
if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {
cccr = m_can_read(cdev, M_CAN_CCCR);
cccr &= ~CCCR_CMR_MASK;
@@ -1655,6 +1653,9 @@ static netdev_tx_t m_can_tx_handler(stru
m_can_write(cdev, M_CAN_CCCR, cccr);
}
m_can_write(cdev, M_CAN_TXBTIE, 0x1);
+
+ can_put_echo_skb(skb, dev, 0, 0);
+
m_can_write(cdev, M_CAN_TXBAR, 0x1);
/* End of xmit function for version 3.0.x */
} else {