Change in flashrom[master]: writeprotect_ranges.c: Use 1UL if left shifting more than 32bits

[Nico Huber (Code Review)]

Attention is currently required from: Angel Pons, Light, Nikolai Artemiev.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/62733 )

Change subject: writeprotect_ranges.c: Use 1UL if left shifting more than 32bits
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Patch Set 4:

(1 comment)

Commit Message:

https://review.coreboot.org/c/flashrom/+/62733/comment/ca7449dd_562a8093 
PS2, Line 12: Still the bug is not fixed :(
> I don't think it would work as the max value that bp_max can take is 15 since the array bits->bp is  […]

The types can't help us because an underflow or a negative `bp_max - 2` both
would result in undefined behavior. From C11 about the shift operators:

"If the value of the right operand is negative or is greater than
  or equal to the width of the promoted left operand, the behavior
  is undefined."

As far as I can see, the bug is only a theoretical one that depends on the
arguments passed to this function (i.e. `bits->bp_bit_count`). I see two
potential solutions: 1. Either add an assert() that would provide a contract
how this function should be called, e.g. on the top of the function:

assert(bits->bp_bit_count > 1);

2. Defensive programming. We could add an `if` that returns an error if
this happens.

Personally, I'm much a fan of 1. But I am not sure if it will be accepted
by scan-build.