Device data will not be allocated in hashfast_detect_one_usb so no point freeing it.
diff --git a/driver-hashfast.c b/driver-hashfast.c
index 35def80..d71686e 100644
--- a/driver-hashfast.c
+++ b/driver-hashfast.c
@@ -328,8 +328,6 @@ static bool hashfast_detect_one_usb(libusb_device *dev, struct usb_find_devices
quit(1, "Failed to usb_alloc_cgpu hashfast");
if (!usb_init(hashfast, dev, found)) {
- free(hashfast->device_data);
- hashfast->device_data = NULL;
hashfast = usb_free_cgpu(hashfast);
return false;
}