Add additional checks for size greater than header size.

Change-Id: Iea64e3df795d1f9299117cbd161b203295211629

R=wfrichar@chromium.org,gauravsh@chromium.org
BUG=chrome-os-partner:2908
TEST=make && make runtests

Review URL: http://codereview.chromium.org/6745027
1 file changed