linux-cve-announce - CVE-2025-39859: ptp: ocp: fix use-after-free bugs causing by ptp_ocp

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Message-ID: <2025091905-CVE-2025-39859-52d5@gregkh>
Date: Fri, 19 Sep 2025 17:28:23 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39859: ptp: ocp: fix use-after-free bugs causing by ptp_ocp_watchdog

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

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

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

ptp: ocp: fix use-after-free bugs causing by ptp_ocp_watchdog

The ptp_ocp_detach() only shuts down the watchdog timer if it is
pending. However, if the timer handler is already running, the
timer_delete_sync() is not called. This leads to race conditions
where the devlink that contains the ptp_ocp is deallocated while
the timer handler is still accessing it, resulting in use-after-free
bugs. The following details one of the race scenarios.

(thread 1)                           | (thread 2)
ptp_ocp_remove()                     |
  ptp_ocp_detach()                   | ptp_ocp_watchdog()
    if (timer_pending(&bp->watchdog))|   bp = timer_container_of()
      timer_delete_sync()            |
                                     |
  devlink_free(devlink) //free       |
                                     |   bp-> //use

Resolve this by unconditionally calling timer_delete_sync() to ensure
the timer is reliably deactivated, preventing any access after free.

The Linux kernel CVE team has assigned CVE-2025-39859 to this issue.


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

	Issue introduced in 5.15 with commit 773bda96492153e11d21eb63ac814669b51fc701 and fixed in 6.16.6 with commit f10d3c7267ac7387a5129d5506c3c5f2460cfd9b
	Issue introduced in 5.15 with commit 773bda96492153e11d21eb63ac814669b51fc701 and fixed in 6.17-rc5 with commit 8bf935cf789872350b04c1a6468b0a509f67afb2

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-2025-39859
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/ptp/ptp_ocp.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/f10d3c7267ac7387a5129d5506c3c5f2460cfd9b
	https://git.kernel.org/stable/c/8bf935cf789872350b04c1a6468b0a509f67afb2