CVE-2026-89502: ring-buffer: Free cpu_buffer::free_page with subbuf_order

CVE-2026-89502: ring-buffer: Free cpu_buffer::free_page with subbuf_order

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

ring-buffer: Free cpu_buffer::free_page with subbuf_order

When sub-buffers use an order greater than 0, cpu_buffer->free_page is
allocated with subbuf_order. Use the correct order for
cpu_buffer->free_page.

The Linux kernel CVE team has assigned CVE-2026-89502 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 6.12.109 with commit 77275ccea06eaf297e8e6ac3fc830cb72086379a
	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 6.18.50 with commit 8c1ecdcdea738efe0494af908f12c0ae3a97fffa
	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.2.4 with commit 81063bbb16c4fcf0136c9117d5e49d3621dd6a1e
	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.3-rc1 with commit 234b1a72e9706fe20c08c96f4374ec8e83b934cb

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-89502
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	kernel/trace/ring_buffer.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/77275ccea06eaf297e8e6ac3fc830cb72086379a
	https://git.kernel.org/stable/c/8c1ecdcdea738efe0494af908f12c0ae3a97fffa
	https://git.kernel.org/stable/c/81063bbb16c4fcf0136c9117d5e49d3621dd6a1e
	https://git.kernel.org/stable/c/234b1a72e9706fe20c08c96f4374ec8e83b934cb