usbdev: fix accepting shorter serial numbers than the real one.

Change-Id: Ife8c4e0a957c4345e27ec9ae9e1480ca80fe505c
---
M usbdev.c
1 file changed, 2 insertions(+), 1 deletion(-)


git pull ssh://review.coreboot.org:29418/flashrom refs/changes/41/34641/1

diff --git a/usbdev.c b/usbdev.c
index 764ac04..7e41235 100644
--- a/usbdev.c
+++ b/usbdev.c
@@ -104,7 +104,8 @@
 	msg_pdbg("Serial number is %s\n", myserial);
 
 	/* Filter out any serial number that does not commence with serialno */
-	return 0 != strncmp(serialno, (char *)myserial, strlen(serialno));
+	return strlen((char *)myserial) == strlen(serialno)
+			&& 0 != strncmp(serialno, (char *)myserial, strlen(serialno));
 }
 
 struct libusb_device_handle *usb_dev_get_by_vid_pid_serial(

