Security: Make sure not to overflow the in memory version of the GBB

This change plumbs the size of the GBB specified in the device tree to the
functions that read it from the flash into memory, and adds checks to those
functions to make sure they don't spill out of the in memory GBB. From a
security standpoint this is a largely theoretical problem since the GBB is
in the read only portion of flash and if that can be modified the machine
is totally compromised, but it's possible somehow an attacker could force
vboot to read the GBB from the wrong place. From a practical perspective
it's not a bad idea to check this to avoid accidental memory corruption.

BUG=chromium-os:24223
TEST=Built and booted on Lumpy. Built for Kaen.

Change-Id: I4f33552f9d27321e73659520b08be52d775a6a9b
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/13228
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>

0 files changed, 0 insertions, 0 deletions