CVE-2026-74634

In the Linux kernel, the following vulnerability has been resolved:

ring-buffer: Prevent subbuf order change when resizing is disabled

Because ring_buffer_subbuf_order_set() frees buffer pages, we can't allow it when resizing is disabled. A non-consuming reader is at risk of use-after-free (rb_advance_iter()).

Return -EBUSY on resize_disabled, matching ring_buffer_resize() behaviour.