linux-cve-announce - CVE-2025-21685: platform/x86: lenovo-yoga-tab2-pro-1380-fastcharger: fix serdev race

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Message-ID: <2025020931-CVE-2025-21685-d720@gregkh>
Date: Sun,  9 Feb 2025 12:36:31 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21685: platform/x86: lenovo-yoga-tab2-pro-1380-fastcharger: fix serdev race

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

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

platform/x86: lenovo-yoga-tab2-pro-1380-fastcharger: fix serdev race

The yt2_1380_fc_serdev_probe() function calls devm_serdev_device_open()
before setting the client ops via serdev_device_set_client_ops(). This
ordering can trigger a NULL pointer dereference in the serdev controller's
receive_buf handler, as it assumes serdev->ops is valid when
SERPORT_ACTIVE is set.

This is similar to the issue fixed in commit 5e700b384ec1
("platform/chrome: cros_ec_uart: properly fix race condition") where
devm_serdev_device_open() was called before fully initializing the
device.

Fix the race by ensuring client ops are set before enabling the port via
devm_serdev_device_open().

Note, serdev_device_set_baudrate() and serdev_device_set_flow_control()
calls should be after the devm_serdev_device_open() call.

The Linux kernel CVE team has assigned CVE-2025-21685 to this issue.

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

	Issue introduced in 6.10 with commit b2ed33e8d486ab2f1920131dd76fab38c8ef3550 and fixed in 6.12.11 with commit 3f67e07873df3c6d9ce2582260b83732e1d3a40b
	Issue introduced in 6.10 with commit b2ed33e8d486ab2f1920131dd76fab38c8ef3550 and fixed in 6.13 with commit 59616a91e5e74833b2008b56c66879857c616006

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-2025-21685
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/platform/x86/lenovo-yoga-tab2-pro-1380-fastcharger.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/3f67e07873df3c6d9ce2582260b83732e1d3a40b
	https://git.kernel.org/stable/c/59616a91e5e74833b2008b56c66879857c616006