linux-cve-announce - CVE-2025-38268: usb: typec: tcpm: move tcpm_queue_vdm

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Message-ID: <2025071007-CVE-2025-38268-3f41@gregkh>
Date: Thu, 10 Jul 2025 09:42:09 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38268: usb: typec: tcpm: move tcpm_queue_vdm_unlocked to asynchronous work

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

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

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

usb: typec: tcpm: move tcpm_queue_vdm_unlocked to asynchronous work

A state check was previously added to tcpm_queue_vdm_unlocked to
prevent a deadlock where the DisplayPort Alt Mode driver would be
executing work and attempting to grab the tcpm_lock while the TCPM
was holding the lock and attempting to unregister the altmode, blocking
on the altmode driver's cancel_work_sync call.

Because the state check isn't protected, there is a small window
where the Alt Mode driver could determine that the TCPM is
in a ready state and attempt to grab the lock while the
TCPM grabs the lock and changes the TCPM state to one that
causes the deadlock. The callstack is provided below:

[110121.667392][    C7] Call trace:
[110121.667396][    C7]  __switch_to+0x174/0x338
[110121.667406][    C7]  __schedule+0x608/0x9f0
[110121.667414][    C7]  schedule+0x7c/0xe8
[110121.667423][    C7]  kernfs_drain+0xb0/0x114
[110121.667431][    C7]  __kernfs_remove+0x16c/0x20c
[110121.667436][    C7]  kernfs_remove_by_name_ns+0x74/0xe8
[110121.667442][    C7]  sysfs_remove_group+0x84/0xe8
[110121.667450][    C7]  sysfs_remove_groups+0x34/0x58
[110121.667458][    C7]  device_remove_groups+0x10/0x20
[110121.667464][    C7]  device_release_driver_internal+0x164/0x2e4
[110121.667475][    C7]  device_release_driver+0x18/0x28
[110121.667484][    C7]  bus_remove_device+0xec/0x118
[110121.667491][    C7]  device_del+0x1e8/0x4ac
[110121.667498][    C7]  device_unregister+0x18/0x38
[110121.667504][    C7]  typec_unregister_altmode+0x30/0x44
[110121.667515][    C7]  tcpm_reset_port+0xac/0x370
[110121.667523][    C7]  tcpm_snk_detach+0x84/0xb8
[110121.667529][    C7]  run_state_machine+0x4c0/0x1b68
[110121.667536][    C7]  tcpm_state_machine_work+0x94/0xe4
[110121.667544][    C7]  kthread_worker_fn+0x10c/0x244
[110121.667552][    C7]  kthread+0x104/0x1d4
[110121.667557][    C7]  ret_from_fork+0x10/0x20

[110121.667689][    C7] Workqueue: events dp_altmode_work
[110121.667697][    C7] Call trace:
[110121.667701][    C7]  __switch_to+0x174/0x338
[110121.667710][    C7]  __schedule+0x608/0x9f0
[110121.667717][    C7]  schedule+0x7c/0xe8
[110121.667725][    C7]  schedule_preempt_disabled+0x24/0x40
[110121.667733][    C7]  __mutex_lock+0x408/0xdac
[110121.667741][    C7]  __mutex_lock_slowpath+0x14/0x24
[110121.667748][    C7]  mutex_lock+0x40/0xec
[110121.667757][    C7]  tcpm_altmode_enter+0x78/0xb4
[110121.667764][    C7]  typec_altmode_enter+0xdc/0x10c
[110121.667769][    C7]  dp_altmode_work+0x68/0x164
[110121.667775][    C7]  process_one_work+0x1e4/0x43c
[110121.667783][    C7]  worker_thread+0x25c/0x430
[110121.667789][    C7]  kthread+0x104/0x1d4
[110121.667794][    C7]  ret_from_fork+0x10/0x20

Change tcpm_queue_vdm_unlocked to queue for tcpm_queue_vdm_work,
which can perform the state check while holding the TCPM lock
while the Alt Mode lock is no longer held. This requires a new
struct to hold the vdm data, altmode_vdm_event.

The Linux kernel CVE team has assigned CVE-2025-38268 to this issue.


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

	Issue introduced in 6.9 with commit cdc9946ea6377e8e214b135ccc308c5e514ba25f and fixed in 6.12.34 with commit 7bdd712abefbec79176ab412d8c623e755c5d0ba
	Issue introduced in 6.9 with commit cdc9946ea6377e8e214b135ccc308c5e514ba25f and fixed in 6.15.3 with commit 1970d34b48cbeceb0c765984c9a6bb204c77f16a
	Issue introduced in 6.9 with commit cdc9946ea6377e8e214b135ccc308c5e514ba25f and fixed in 6.16-rc1 with commit 324d45e53f1a36c88bc649dc39e0c8300a41be0a

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-2025-38268
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/usb/typec/tcpm/tcpm.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/7bdd712abefbec79176ab412d8c623e755c5d0ba
	https://git.kernel.org/stable/c/1970d34b48cbeceb0c765984c9a6bb204c77f16a
	https://git.kernel.org/stable/c/324d45e53f1a36c88bc649dc39e0c8300a41be0a