vb2api: pad digest buffers if they are larger than digest sizes

Extending tpm PCRs in case of TPM2 requires 32 bit values, some
digests pre-calculated in vboot source code are 20 bytes in size. To
make sure that PCR extension is consistent, pad remaining buffer space
when a 20 byte digest is returned in a 32 byte buffer.

BRANCH=none
BUG=chrome-os-partner:50645
TEST=did not verify much, made sure that PCR extension commands
     triggered by coreboot succeed.

Change-Id: Ib16bdf782f18a6106eadb4b880cd1e67b56ad6db
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/358175
Reviewed-by: Randall Spangler <rspangler@chromium.org>
(cherry picked from commit cd341a0cd7d698b816b55a0f6e2e9ae9aeeea3bb)
Reviewed-on: https://chromium-review.googlesource.com/358933
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>
1 file changed