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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: a8f820a380 ("can: add Virtual CAN Tunnel driver (vxcan)")
Link: https://lore.kernel.org/r/20210120114137.200019-3-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
master
Vincent Mailhol 2021-01-20 20:41:36 +09:00 committed by Marc Kleine-Budde
parent 03f16c5075
commit 75854cad5d
1 changed files with 4 additions and 2 deletions
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6
drivers/net/can/vxcan.c
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@ -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: