Some users have encountered situations, where GoPro Cineform files have a truncated Duration.
One PrElements user encountered this issue, and found the solution from Cineform. It is posted to the PrE Forum, but the download (other than the Path for PrE) should work in PrPro too: http://forums.adobe.com/message/5437849?tstart=0#5437849
Good luck, and hope that this helps,
Here is how its done in Premiere Pro
This is the link for the avi importer: http://software.gopro.com/PC/CFHD_AVI_Importer.prm
Copy/paste in Program Files / Adobe / Common / Plugins / CS6 or 7.0 / Media Core / Cineform
Thank you for that bit of info.