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From: Marc Kleine-Budde <mkl@pengutronix.de>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org,
	kernel@pengutronix.de,
	Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
	Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [net 2/3] can: vxcan: vxcan_xmit: fix use after free bug
Date: Wed, 20 Jan 2021 13:52:01 +0100	[thread overview]
Message-ID: <20210120125202.2187358-3-mkl@pengutronix.de> (raw)
In-Reply-To: <20210120125202.2187358-1-mkl@pengutronix.de>

From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

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: a8f820a380a2 ("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>
---
 drivers/net/can/vxcan.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/vxcan.c b/drivers/net/can/vxcan.c
index fa47bab510bb..f9a524c5f6d6 100644
--- a/drivers/net/can/vxcan.c
+++ b/drivers/net/can/vxcan.c
@@ -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:
-- 
2.29.2



  parent reply	other threads:[~2021-01-20 20:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-20 12:51 pull-request: can 2021-01-20 Marc Kleine-Budde
2021-01-20 12:52 ` [net 1/3] can: dev: can_restart: fix use after free bug Marc Kleine-Budde
2021-01-20 20:40   ` patchwork-bot+netdevbpf
2021-01-20 12:52 ` Marc Kleine-Budde [this message]
2021-01-20 12:52 ` [net 3/3] can: peak_usb: fix use after free bugs Marc Kleine-Budde
2021-01-20 17:19 ` pull-request: can 2021-01-20 Jakub Kicinski
2021-01-20 20:20   ` Marc Kleine-Budde
2021-01-20 20:36     ` Jakub Kicinski
2021-01-20 21:03       ` Marc Kleine-Budde
2021-01-20 20:40 ` patchwork-bot+netdevbpf

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