netlabel: fix out-of-bounds memory accesses

In the Linux kernel, the following vulnerability has been resolved: netlabel: fix out-of-bounds memory accesses There are two array out-of-bounds memory accesses, one in cipso_v4_map_lvl_valid(), the other in netlbl_bitmap_walk(). Both errors are embarassingly simple, and the fixes are straightforward. As a FYI for anyone backporting this patch to kernels prior to v4.8, you'll want to apply the netlbl_bitmap_walk() patch to cipso_v4_bitmap_walk() as netlbl_bitmap_walk() doesn't exist before Linux v4.8.