cgptlib: Minor edge case fixes

This patch fixes a sanitizer issue in cgpt where a GPT entries array may
have been passed even though it was not loaded from disk (parsing an
uninitialized buffer). The GPT library seems to have been written with
the assumption that both headers and entries would always be loaded and
it could recover even if only the primary header and the secondary
entries were valid. In practice, this doesn't really work because the
caller doesn't know how to read entries for an invalid header.
Therefore, change the code so that entries are only assumed to be loaded
for valid headers.

Also fix some minor problems with loading GPTs by aligning sizes up (not
down) to the next sector boundary and making sure we always allocate the
maximum amount of space for entry arrays, even if the current header may
not need that much (in case a repair wants to overwrite it).

This practically reverts CL:276766 which becomes obsolete (and was
really just a dirty hack to hide an underlying problem).

BRANCH=none
BUG=chromium:1017797
TEST=make runtests

Change-Id: I86c601dc074261d53f013b98ae214efdc44f3563
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1885098
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

0 files changed, 0 insertions, 0 deletions