Security fixes for LoadKernel()

Security fixes for LoadKernel()

1) kernel_subkey is one of the input parameters; not read off disk.  KeyBlockVerify() now verifies it's not NULL unless we're only using the hash.

2) Added a check for kernel size vs. buffer size.

3) Added a check to make sure kbuf_sectors is nonzero.

BUG=chrome-os-partner:704
TEST=make && make runtests

[Bill Richardson, 2010-08-18 23:33:28]

Hm.

http://codereview.chromium.org/3186013/diff/1/2
File firmware/lib/vboot_kernel.c (right):

http://codereview.chromium.org/3186013/diff/1/2#newcode308
firmware/lib/vboot_kernel.c:308: body_offset /= blba;
Use a new variable for body_offset here. body_offset is bytes up to this point,
sectors afterward. That's confusing.

[Randall Spangler, 2010-08-19 00:19:28]

PTAL

http://codereview.chromium.org/3186013/diff/1/2
File firmware/lib/vboot_kernel.c (right):

http://codereview.chromium.org/3186013/diff/1/2#newcode308
firmware/lib/vboot_kernel.c:308: body_offset /= blba;
On 2010/08/18 23:33:28, Bill Richardson wrote:
> Use a new variable for body_offset here. body_offset is bytes up to this
point,
> sectors afterward. That's confusing.

Done.

[Bill Richardson, 2010-08-19 00:33:17]

Thanks. LGTM.