From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Date: Wed, 20 Jan 2021 11:41:35 +0000 (+0900)
Subject: can: dev: can_restart: fix use after free bug
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=03f16c5075b22c8902d2af739969e878b0879c94;p=linux.git

can: dev: can_restart: fix use after free bug

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: 39549eef3587 ("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>
---

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 3486704c8a957..8b1ae023cb218 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -592,11 +592,11 @@ 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->len;
 
+	netif_rx_ni(skb);
+
 restart:
 	netdev_dbg(dev, "restarted\n");
 	priv->can_stats.restarts++;