[PATCH net] net: adin1110: flush rx_mode_work on stop to avoid use-after-free

[hyunjungg <hj351016@gmail.com>]

From: Hyunjung Ko <hj351016@gmail.com>

adin1110_set_rx_mode() defers the hardware filter update to rx_mode_work
(adin1110_rx_mode_work), which dereferences the port private data via
container_of(). adin1110_net_stop() flushes tx_work but not rx_mode_work,
and nothing else ever cancels it.

The netdevs are registered with devm_register_netdev(), so on unbind the
port_priv (netdev_priv) memory is freed by devres. A rx-mode update
queued shortly before the interface goes down can therefore still be
pending after the device is freed, and adin1110_rx_mode_work() then runs
against freed memory (use-after-free).

Flush rx_mode_work in adin1110_net_stop(), next to the existing tx_work
flush, so both deferred works are drained before the device can be torn
down. adin1110_rx_mode_work() does not re-queue itself.

Found by static analysis and code review; not tested on real hardware
(needs an ADIN1110/ADIN2111 SPI Ethernet device).

Fixes: bc93e19d088b ("net: ethernet: adi: Add ADIN1110 support")
Cc: stable@vger.kernel.org
Signed-off-by: Hyunjung Ko <hj351016@gmail.com>
---
 drivers/net/ethernet/adi/adin1110.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/adi/adin1110.c b/drivers/net/ethernet/adi/adin1110.c
index 53fac3d..788cf4d 100644
--- a/drivers/net/ethernet/adi/adin1110.c
+++ b/drivers/net/ethernet/adi/adin1110.c
@@ -956,6 +956,7 @@ static int adin1110_net_stop(struct net_device *net_dev)
 
 	netif_stop_queue(port_priv->netdev);
 	flush_work(&port_priv->tx_work);
+	flush_work(&port_priv->rx_mode_work);
 	phy_stop(port_priv->phydev);
 
 	return 0;
-- 
2.43.0