[PATCH 4.9 032/129] usbnet: ignore endpoints with invalid wMaxPacketSize

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Bjørn Mork <bjorn@mork.no>

[ Upstream commit 8d3d7c2029c1b360f1a6b0a2fca470b57eb575c0 ]

Endpoints with zero wMaxPacketSize are not usable for transferring
data. Ignore such endpoints when looking for valid in, out and
status pipes, to make the drivers more robust against invalid and
meaningless descriptors.

The wMaxPacketSize of these endpoints are used for memory allocations
and as divisors in many usbnet minidrivers. Avoiding zero is therefore
critical.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/usb/usbnet.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -114,6 +114,11 @@ int usbnet_get_endpoints(struct usbnet *
 			int				intr = 0;
 
 			e = alt->endpoint + ep;
+
+			/* ignore endpoints which cannot transfer data */
+			if (!usb_endpoint_maxp(&e->desc))
+				continue;
+
 			switch (e->desc.bmAttributes) {
 			case USB_ENDPOINT_XFER_INT:
 				if (!usb_endpoint_dir_in(&e->desc))