vm audit: add VM_DONTEXPAND to mmap for drivers that need it

Drivers that register a ->fault handler, but do not range-check the
offset argument, must set VM_DONTEXPAND in the vm_flags in order to
prevent an expanding mremap from overflowing the resource.

I've audited the tree and attempted to fix these problems (usually by
adding VM_DONTEXPAND where it is not obvious).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ncpfs/mmap.c

@@ -50,10 +50,6 @@ static int ncp_file_mmap_fault(struct vm_area_struct *area,
 	pos = vmf->pgoff << PAGE_SHIFT;
 
 	count = PAGE_SIZE;
-	if ((unsigned long)vmf->virtual_address + PAGE_SIZE > area->vm_end) {
-		WARN_ON(1); /* shouldn't happen? */
-		count = area->vm_end - (unsigned long)vmf->virtual_address;
-	}
 	/* what we can read in one go */
 	bufsize = NCP_SERVER(inode)->buffer_size;