CVE-2026-89503

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

ring-buffer: Fix subbuf resize race with ring buffer alloc read page()

ring buffer alloc read page() is racy with ring buffer subbuf order set, it can allocate a reader page with an outdated order. This isn't a big issue, the user can still re-allocate a new reader page and try again.

However, what is more problematic is if the value of subbuf order changes in the middle of ring buffer alloc read page(). In that case, bpage->order might not match the actual allocated memory.

Use bpage->order for the allocation to prevent this race.