zd1211rw: fix NULL-deref at probe

commit ca260ece upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer or accessing memory beyond the endpoint array should a
malicious device lack the expected endpoints.

Fixes: a1030e92 ("[PATCH] zd1211rw: Convert installer CDROM device into WLAN device")
Cc: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/wireless/zd1211rw/zd_usb.c

@@ -1278,6 +1278,9 @@ static int eject_installer(struct usb_interface *intf)
 	u8 bulk_out_ep;
 	int r;
 
+	if (iface_desc->desc.bNumEndpoints < 2)
+		return -ENODEV;
+
 	/* Find bulk out endpoint */
 	for (r = 1; r >= 0; r--) {
 		endpoint = &iface_desc->endpoint[r].desc;