Subject: [PATCH net 1/3] net: lan78xx: add missing endpoint sanity check

From: Johan Hovold <[email-masked]>
Date: Tue, 28 Jul 2020 14:10:29 +0200

Add the missing endpoint sanity check to prevent a NULL-pointer
dereference should a malicious device lack the expected endpoints.

Note that the driver has a broken endpoint-lookup helper,
lan78xx_get_endpoints(), which can end up accepting interfaces in an
altsetting without endpoints as long as *some* altsetting has a bulk-in
and a bulk-out endpoint.

Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Cc: [email-masked] <[email-masked]>
Signed-off-by: Johan Hovold <[email-masked]>
---
 drivers/net/usb/lan78xx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index eccbf4cd7149..d7162690e3f3 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -3759,6 +3759,11 @@ static int lan78xx_probe(struct usb_interface *intf,
 	netdev->max_mtu = MAX_SINGLE_PACKET_SIZE;
 	netif_set_gso_max_size(netdev, MAX_SINGLE_PACKET_SIZE - MAX_HEADER);
 
+	if (intf->cur_altsetting->desc.bNumEndpoints < 3) {
+		ret = -ENODEV;
+		goto out3;
+	}
+
 	dev->ep_blkin = (intf->cur_altsetting)->endpoint + 0;
 	dev->ep_blkout = (intf->cur_altsetting)->endpoint + 1;
 	dev->ep_intr = (intf->cur_altsetting)->endpoint + 2;
-- 
2.26.2