drm/shmem_helper: Check VMA boundaries for PMD mappings

In the Linux kernel, the following vulnerability has been resolved: drm/shmem_helper: Check VMA boundaries for PMD mappings In the ->huge_fault handler do not install a PMD huge page mapping if the huge page exceeds the boundaries of the VMA. All other ->huge_fault handlers have similar checks and the resulting mapping will trigger a VM_BUG_ON_VMA() if it ever reaches copy_pmd_range().