Commit 75854cad authored by Vincent Mailhol's avatar Vincent Mailhol Committed by Marc Kleine-Budde
Browse files

can: vxcan: vxcan_xmit: fix use after free bug 

After calling netif_rx_ni(skb), dereferencing skb is unsafe.
Especially, the canfd_frame cfd which aliases skb memory is accessed
after the netif_rx_ni().

Fixes: a8f820a3 ("can: add Virtual CAN Tunnel driver (vxcan)")
Link: https://lore.kernel.org/r/20210120114137.200019-3-mailhol.vincent@wanadoo.fr


Signed-off-by: default avatarVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 03f16c50

drivers/net/can/vxcan.c

+4 −2
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev) 
	struct net_device *peer;

	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;

	struct net_device_stats *peerstats, *srcstats = &dev->stats;

	u8 len;



	if (can_dropped_invalid_skb(dev, skb))

		return NETDEV_TX_OK;
@@ -61,12 +62,13 @@ static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev) 
	skb->dev        = peer;

	skb->ip_summed  = CHECKSUM_UNNECESSARY;



	len = cfd->len;

	if (netif_rx_ni(skb) == NET_RX_SUCCESS) {

		srcstats->tx_packets++;

		srcstats->tx_bytes += cfd->len;

		srcstats->tx_bytes += len;

		peerstats = &peer->stats;

		peerstats->rx_packets++;

		peerstats->rx_bytes += cfd->len;

		peerstats->rx_bytes += len;

	}



out_unlock: