linux-cve-announce - CVE-2025-39954: clk: sunxi-ng: mp: Fix dual-divider clock rate readback

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Message-ID: <2025100939-CVE-2025-39954-e887@gregkh>
Date: Thu,  9 Oct 2025 11:47:40 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39954: clk: sunxi-ng: mp: Fix dual-divider clock rate readback

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

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

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

clk: sunxi-ng: mp: Fix dual-divider clock rate readback

When dual-divider clock support was introduced, the P divider offset was
left out of the .recalc_rate readback function. This causes the clock
rate to become bogus or even zero (possibly due to the P divider being
1, leading to a divide-by-zero).

Fix this by incorporating the P divider offset into the calculation.

The Linux kernel CVE team has assigned CVE-2025-39954 to this issue.


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

	Issue introduced in 6.15 with commit 45717804b75eda8a76eacc04509ca4d68dd2caaf and fixed in 6.16.9 with commit 40108f69c372af3aea73e7829d6849a44638d662
	Issue introduced in 6.15 with commit 45717804b75eda8a76eacc04509ca4d68dd2caaf and fixed in 6.17 with commit 25fbbaf515acd13399589bd5ee6de5f35740cef2

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-2025-39954
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:
	drivers/clk/sunxi-ng/ccu_mp.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/40108f69c372af3aea73e7829d6849a44638d662
	https://git.kernel.org/stable/c/25fbbaf515acd13399589bd5ee6de5f35740cef2