CVE-2026-80755 selinux: reject a permission value exceeding the class permission count

CVE-2026-80755 affects the Linux kernel SELinux subsystem. The root cause is in perm_read(), which bounds a permission value by SEL_VEC_MAX but never by nprim (the count of permissions for the owning class or common, taken verbatim from the policy image). As a result, security_get_permissions() w...