Over voltage GPIO in STM32F
The datasheet is here:

http://www.st.com/content/ccc/resource/technical/document/datasheet/03/b4/b2/36/4c/72/49/29/DM00071990.pdf/files/DM00071990.pdf/jcr:content/translations/en.DM00071990.pdf

From page 52:

So if look for I/O pins in the table that have I/O structure "FT".  These can tolerate inputs of up to 5V.  (This appears to be most of the I/O pins.)

I learned this procedure from this Olimex forum post: https://www.olimex.com/forum/index.php?topic=1301.msg6060#msg6060