vboot: fix workbuf_used value after storing GBB header
After storing the GBB header on the workbuf, the offset of wb.buf
is stored into workbuf_used by incorrectly using ctx as the
pointer base, rather than sd (which corresponds to the start of
the workbuf). This subtracts 8 bytes from the correct value of
workbuf_used, and leaves the last 8 bytes of the GBB header
vulnerable to being overwritten with any VB2_WORKBUF_ALIGN values
less than 16.
Also update the relevant vb2_misc_tests check to account for
GBB headers with non-aligned sizes (currently it is 128 bytes).
BUG=b:124141368, chromium:1027846
TEST=Test with various VB2_WORKBUF_ALIGN values
BRANCH=none
Change-Id: I862d29155ce08df6911c277f8ce8c703ffaf1df7
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1932276
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
2 files changed
