mprotect outbound check.

[Jeff Xu]

Noticed there is a slight change for mprotect between 6.1 and 6.4 RC1

For example:
Consider the case below:
1 mmap(0x5000000, PAGE_SIZE,  ...)
2 mprotect(0x5000000, PAGE_SIZE*4, ...)

in 6.1 and before, 2 will fail, and in 6.4 RC1, it will pass.

I know that munmap will accept out-of-bound cases like this (because
memory is freed anyway).

Is this change intentional ?

Thanks!
Best regards,
-Jeff