can: hi311x: hi3110_can_ist(): fix potential use-after-free

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@amarulasolutions.com>
Link: https://patch.msgid.link/20241122221650.633981-5-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/spi/hi311x.c b/drivers/net/can/spi/hi311x.c
index 148d974ebb210778cb1b0b96305a513b4e7af52c..b67464df25ffeb1be0168a7069784a7cb7184bcd 100644 (file)
--- 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);
                        }
                }