LAB2_1B :SAM3U Serial buffers OVERRUN

Embedded Security ChipWhisperer Software
1

I get this error:
" WARNING:root:SAM3U Serial buffers OVERRUN - data loss has occurred."
when running Lab 2_1B Power Analysis for Password Bypass. But it seems like the code still runs fine. i am able to find the correct password, but it does take a very long time.

Any tips with how to fix. i tried to look at some old forum posts which included removing some delays in the basic-passwdcheck.c file but it did not work.

2

From a previous post on this issue:

The serial buffer overrun message is caused by all the extraneous my_puts() messages that are output at the start of the while loop in main(); if you comment them out the error will go away. I’m not sure why these are popping up now; regardless, you should be able to successfully complete the lab.

1 Like
3

I’m getting this same error on the same lab, but as mentioned above the lab still seems to work, or could comment out those my_puts() calls, but that got me wondering, where/how do we view those my_puts messages?

I’m guessing because at the beginning of the main method it calls init_uart() that those messages are being printed over UART? How can we connect to that to see it? I’ve got my Husky connected to the CW313 which has the SAM4S inserted in it.

Do I just connect to the Husky with picocom or screen or something similar to see that output? What are those messages for exactly if you can’t see them in the lab anyway? :thinking:

4

In all our labs, target communication is UART on the TIO1/TIO2 lines (CW305 FPGA labs are the exception).

What’s sent by the target is read (look at the cap_pass_trace() function), we just don’t use it for the attack.

1 Like
5

Yes, you do a"man in the middle" and see the serial communication between the capture device and the target if you use putty, picocom or any other serial terminal connected to the com port of the capture device.
At least with the nano nothing special is required, you can see the welcome screen and the password tries, even you can send commands to the target, but if you want to try passwords manually you must comment the while(1) in the last lines of the “basic password check” source code to let you try more than 1 password (as it is the MCU starts idling after first try)