Commit bbc6847b authored Jan 20, 2021 by Vincent Mailhol Committed by Greg Kroah-Hartman Jan 30, 2021

can: dev: can_restart: fix use after free bug

[ Upstream commit 03f16c5075b22c8902d2af739969e878b0879c94 ]

After calling netif_rx_ni(skb), dereferencing skb is unsafe.
Especially, the can_frame cf which aliases skb memory is accessed
after the netif_rx_ni() in:
      stats->rx_bytes += cf->len;

Reordering the lines solves the issue.

Fixes: 39549eef ("can: CAN Network device driver and Netlink interface")
Link: https://lore.kernel.org/r/20210120114137.200019-2-mailhol.vincent@wanadoo.fr


Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 9a492875

drivers/net/can/dev.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -555,11 +555,11 @@ static void can_restart(struct net_device *dev)
		}
		cf->can_id \|= CAN_ERR_RESTARTED;

		netif_rx_ni(skb);

		stats->rx_packets++;
		stats->rx_bytes += cf->can_dlc;

		netif_rx_ni(skb);

		restart:
		netdev_dbg(dev, "restarted\n");
		priv->can_stats.restarts++;