[XS] Change in coreboot[main]: [NEEDS TEST] region: Check for overflows after offset calculation

[Nico Huber (Code Review)]

Attention is currently required from: Julius Werner.

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79945?usp=email )

Change subject: [NEEDS TEST] region: Check for overflows after offset calculation
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Patch Set 3:

(1 comment)

File src/commonlib/region.c:

https://review.coreboot.org/c/coreboot/+/79945/comment/5ddb4a65_63635f9d :
PS3, Line 25: 	return region_end(inner) - 1 >= region_offset(inner) &&
> I haven't been able to think of a use case for it yet, so I'd say let's try forbidding it and see if […]

Technically, we don't have to decide. It's just a little more code to
support both cases. Anyway, what do you think about leaving an assert in
region_is_subregion()? and all the other public APIs? would that be too
much overhead?