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Chia-Lin Kao (AceLan) e0b291fe11 usb: core: port: Deattach Type-C connector on component unbind
connector_unbind() is the mirror of connector_bind(), but it is missing
the symmetric call to typec_deattach() that connector_bind() makes via:

    if (port_dev->child)
        typec_attach(port_dev->connector, &port_dev->child->dev);

When a Thunderbolt dock is unplugged, two teardown paths race:

1. The component framework calls connector_unbind() first, which sets
   port_dev->connector = NULL without calling typec_deattach().  This
   leaves port->usb2_dev/port->usb3_dev in struct typec_port pointing at
   the USB device that is about to be freed.

2. usb_disconnect() then calls typec_deattach(port_dev->connector, ...),
   but port_dev->connector is already NULL, so the call is a no-op and
   port->usb2_dev is never cleared.

3. Concurrently, UCSI detects a PD partner-disconnect event and calls
   typec_unregister_partner(), which reads port->usb2_dev (now a dangling
   pointer to freed memory) and passes it to typec_partner_unlink_device()
   -> sysfs_remove_link() -> dev_name() on the freed device, corrupting
   the typec/UCSI partner state.

This corruption leaves the Thunderbolt tunnel in an inconsistent state on
the next dock hot-plug.  On affected hardware the dock's I225/igc NIC fails
to enumerate: AER fires a slot reset while the igc driver is still
initialising ("PCIe link lost"), and the subsequent igc_reset attempt hits
igc_rd32 on an already-detached device:

    igc 0000:2e:00.0 eth0: PCIe link lost, device now detached
    igc: Failed to read reg 0x0!
    WARNING: CPU: 9 PID: 129 at drivers/net/ethernet/intel/igc/igc_main.c:7005
             igc_rd32+0xa4/0xc0 [igc]
    Call Trace:
     igc_disable_pcie_master+0x16/0xa0 [igc]
     igc_reset_hw_base+0x14/0x170 [igc]
     igc_reset+0x63/0x110 [igc]
     igc_io_slot_reset+0x9e/0xd0 [igc]
     report_slot_reset+0x5d/0xc0
     pcie_do_recovery+0x209/0x400
     aer_isr_one_error_type+0x235/0x430
     aer_isr+0x4e/0x80
     irq_thread+0xf4/0x1f0

4. UCSI later handles the PD partner-disconnect and calls
   typec_unregister_partner(), which still sees the stale port->usb2_dev
   and tries to remove its sysfs link a second time:

   kernfs: can not remove 'typec', no directory
   WARNING: CPU: 6 PID: 55 at fs/kernfs/dir.c:1706 kernfs_remove_by_name_ns+0xe9/0xf0
   Workqueue: events ucsi_handle_connector_change [typec_ucsi]
   Call Trace:
    sysfs_remove_link+0x19/0x50
    typec_unregister_partner+0x6e/0x120 [typec]
    ucsi_unregister_partner+0x107/0x150 [typec_ucsi]
    ucsi_handle_connector_change+0x3ec/0x490 [typec_ucsi]
    process_one_work+0x18e/0x3e0
    worker_thread+0x2e3/0x420
    kthread+0x10a/0x230
    ret_from_fork+0x121/0x140
    ret_from_fork_asm+0x1a/0x30

   With worse timing the same stale pointer is dereferenced after the
   backing memory is freed, turning the warning into a use-after-free.

Fix the asymmetry: call typec_deattach() before clearing
port_dev->connector, matching what connector_bind() does on the bind side.
typec_partner_deattach() is already protected by port->partner_link_lock,
so it serialises safely with the concurrent typec_unregister_partner() path.

Fixes: 11110783f5 ("usb: Inform the USB Type-C class about enumerated devices")
Cc: stable <stable@kernel.org>
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://patch.msgid.link/20260611071201.1235545-1-acelan.kao@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-07-16 17:11:22 +02:00
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Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

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* New Kernel Developer - Getting started with kernel development
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* Security Expert - Hardening and vulnerability analysis
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* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
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---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
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* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
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* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
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Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


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=========================

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