netdev - [PATCH net 05/15] can: hi311x: hi3110_can_ist(): fix potential use-after-free

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Message-ID: <20241202090040.1110280-6-mkl@pengutronix.de>
Date: Mon,  2 Dec 2024 09:55:39 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	kuba@...nel.org,
	linux-can@...r.kernel.org,
	kernel@...gutronix.de,
	Dario Binacchi <dario.binacchi@...rulasolutions.com>,
	Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net 05/15] can: hi311x: hi3110_can_ist(): fix potential use-after-free

From: Dario Binacchi <dario.binacchi@...rulasolutions.com>

The commit a22bd630cfff ("can: hi311x: do not report txerr and rxerr
during bus-off") removed the reporting of rxerr and txerr even in case
of correct operation (i. e. not bus-off).

The error count information added to the CAN frame after netif_rx() is
a potential use after free, since there is no guarantee that the skb
is in the same state. It might be freed or reused.

Fix the issue by postponing the netif_rx() call in case of txerr and
rxerr reporting.

Fixes: a22bd630cfff ("can: hi311x: do not report txerr and rxerr during bus-off")
Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
Link: https://patch.msgid.link/20241122221650.633981-5-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/hi311x.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/spi/hi311x.c b/drivers/net/can/spi/hi311x.c
index 148d974ebb21..b67464df25ff 100644
--- a/drivers/net/can/spi/hi311x.c
+++ b/drivers/net/can/spi/hi311x.c
@@ -671,9 +671,9 @@ static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
 			tx_state = txerr >= rxerr ? new_state : 0;
 			rx_state = txerr <= rxerr ? new_state : 0;
 			can_change_state(net, cf, tx_state, rx_state);
-			netif_rx(skb);
 
 			if (new_state == CAN_STATE_BUS_OFF) {
+				netif_rx(skb);
 				can_bus_off(net);
 				if (priv->can.restart_ms == 0) {
 					priv->force_quit = 1;
@@ -684,6 +684,7 @@ static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
 				cf->can_id |= CAN_ERR_CNT;
 				cf->data[6] = txerr;
 				cf->data[7] = rxerr;
+				netif_rx(skb);
 			}
 		}
 
-- 
2.45.2