[PATCH] net: usb: cx82310_eth: stop parsing reboot marker as packet

["Tianchu Chen" <tianchu.chen@linux.dev>]

From: Tianchu Chen <flynnnchen@tencent.com>

Discovered by Atuin - Automated Vulnerability Discovery Engine.

cx82310_rx_fixup() treats an RX length of 0xffff as a device reboot
marker and schedules work to re-enable ethernet mode, but then continues
processing the marker as a normal packet length. This is an out-of-bounds
heap write controlled by the usb device.

Return immediately after scheduling the recovery work so the marker skb
is dropped instead of being assembled as packet data.

Fixes: ca139d76b0d9 ("cx82310_eth: re-enable ethernet mode after router reboot")
Cc: stable@vger.kernel.org
Signed-off-by: Tianchu Chen <flynnnchen@tencent.com>
---
 drivers/net/usb/cx82310_eth.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/usb/cx82310_eth.c b/drivers/net/usb/cx82310_eth.c
index 068acb052..5df657acf 100644
--- a/drivers/net/usb/cx82310_eth.c
+++ b/drivers/net/usb/cx82310_eth.c
@@ -282,6 +282,7 @@ static int cx82310_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 		if (len == 0xffff) {
 			netdev_info(dev->net, "router was rebooted, re-enabling ethernet mode");
 			schedule_work(&priv->reenable_work);
+			return 0;
 		} else if (len > CX82310_MTU) {
 			netdev_err(dev->net, "RX packet too long: %d B\n", len);
 			return 0;
-- 
2.51.0