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 <bj...@mork.no>
---
 drivers/net/usb/usbnet.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 58952a79b05f..dbea2136d901 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -100,6 +100,11 @@ int usbnet_get_endpoints(struct usbnet *dev, struct 
usb_interface *intf)
                        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))
-- 
2.20.1

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