CVE-2026-74602: ring-buffer: Initialise reader page order in rb_allocate_cpu_buffer()

Greg Kroah-Hartman <[email protected]>
Newsgroups org.kernel.vger.linux-cve-announce
Message-ID <2026082215-CVE-2026-74602-b084@gregkh>
From: Greg Kroah-Hartman <[email protected]>

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

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

ring-buffer: Initialise reader page order in rb_allocate_cpu_buffer()

In rb_allocate_cpu_buffer(), bpage->order was omitted, leaving it as 0.
This is an issue for a ring-buffer with subbufs bigger than PAGE_SIZE if
when freed: free_buffer_page() relies on this value. Align the value
with the actual allocation size (buffer::subbuf_order).

The Linux kernel CVE team has assigned CVE-2026-74602 to this issue.


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

	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 6.18.45 with commit 2e37f2bf111429fbfa4d985b12df3ba496ca70aa
	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.1.9 with commit 3b3e0a6ee5bb3ac000f135beef26b2b7ed1a771a
	Issue introduced in 6.8 with commit f9b94daa542a8d2532f0930f01cd9aec2d19621b and fixed in 7.2 with commit 6d014e44b68ddd43f71288d2a4dbb1a259869149

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-2026-74602
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/2e37f2bf111429fbfa4d985b12df3ba496ca70aa
	https://git.kernel.org/stable/c/3b3e0a6ee5bb3ac000f135beef26b2b7ed1a771a
	https://git.kernel.org/stable/c/6d014e44b68ddd43f71288d2a4dbb1a259869149
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