FAILED: patch "[PATCH] can: m_can: m_can_tx_handler(): fix use after free of skb" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-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 <[email protected]>.

thanks,

greg k-h

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

From 2e8e79c416aae1de224c0f1860f2e3350fa171f8 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <[email protected]>
Date: Thu, 17 Mar 2022 08:57:35 +0100
Subject: [PATCH] can: m_can: m_can_tx_handler(): fix use after free of skb

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.

index 1a4b56f6fa8c..b3b5bc1c803b 100644
@@ -1637,8 +1637,6 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 		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(struct m_can_classdev *cdev)
 			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 {

Hi Greg,

Here is the backport, will also apply to 4.14-stable.

--
Regards
Sudip

From d6c487aeeb07c876dbc5c9b21aae004ea2e07037 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <[email protected]>
Date: Thu, 17 Mar 2022 08:57:35 +0100
Subject: [PATCH] can: m_can: m_can_tx_handler(): fix use after free of skb

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.

---
 drivers/net/can/m_can/m_can.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index f5f1367d40d5c..4b88fabbdcbaa 100644
@@ -1438,8 +1438,6 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 					 M_CAN_FIFO_DATA(i / 4),
 					 *(u32 *)(cf->data + i));
 
-		can_put_echo_skb(skb, dev, 0);
-
 		if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
 			cccr = m_can_read(priv, M_CAN_CCCR);
 			cccr &= ~(CCCR_CMR_MASK << CCCR_CMR_SHIFT);

@@ -1456,6 +1454,9 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 			m_can_write(priv, M_CAN_CCCR, cccr);
 		}
 		m_can_write(priv, M_CAN_TXBTIE, 0x1);
+
+		can_put_echo_skb(skb, dev, 0);
+
 		m_can_write(priv, M_CAN_TXBAR, 0x1);
 		/* End of xmit function for version 3.0.x */
 	} else {

2.30.2