kernel: mm/pagewalk.c: walk_hugetlb_range function mishandles holes in hugetlb ranges causing information leak

The walkhugetlbrange function in 'mm/pagewalk.c' file in the Linux kernel from v4.0-rc1 through v4.15-rc1 mishandles holes in hugetlb ranges. This allows local users to obtain sensitive information from uninitialized kernel memory via crafted use of the mincore system call...