selinux: reject a permission value exceeding the class permission count

In the Linux kernel, the following vulnerability has been resolved: selinux: reject a permission value exceeding the class permission count perm_read() bounds a permission value by SEL_VEC_MAX but never by the nprim of the owning class or common, which is taken verbatim from the policy image. security_get_permissions() then writes perms[value - 1] into an nprim-sized kcalloc() array, so a class declaring fewer permissions than its largest permission value drives an out-of-bounds heap write. The top-level symbol tables are validated this way; the nested per-class permission table is not. Reject a permission whose value exceeds nprim, which is already set when perm_read() runs. Well-formed policies are unaffected. [PM: tweak comment for line length]

Where it's fixed