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[34.147.127.12]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c15ad882342sm144491666b.28.2026.07.07.07.17.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Jul 2026 07:17:40 -0700 (PDT) From: Andrei Kuchynski To: Heikki Krogerus , Jameson Thies , Benson Leung , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , Abhishek Pandit-Subedi , Pooja Katiyar , Johan Hovold , Hsin-Te Yuan , Myrrh Periwinkle , Linyu Yuan , Jack Pham , Andrei Kuchynski , stable@vger.kernel.org Subject: [PATCH] usb: typec: ucsi: Fix race condition and ordering in port unregistration Date: Tue, 7 Jul 2026 14:17:36 +0000 Message-ID: <20260707141736.1635698-1-akuchynski@chromium.org> X-Mailer: git-send-email 2.55.0.rc2.803.g1fd1e6609c-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A synchronization issue exists during port unregistration where pending partner work items can race against workqueue destruction, leading to use-after-free conditions: cros_ec_ucsi cros_ec_ucsi.3.auto: error -ETIMEDOUT: PPM init failed BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:__queue_work+0x83/0x4a0 Call Trace: __cfi_delayed_work_timer_fn+0x10/0x10 run_timer_softirq+0x3b6/0xbd0 sched_clock_cpu+0xc/0x110 irq_exit_rcu+0x18d/0x330 fred_sysvec_apic_timer_interrupt+0x5e/0x80 Fix this by ensuring strict ordering and proper serialization during teardown: 1. Move ucsi_unregister_partner() to the beginning of the teardown sequence and protect it under the connector mutex lock. 2. Ensure all pending partner tasks are explicitly flushed and finished before the workqueue is destroyed. 3. Switch from mod_delayed_work() to a cancel_delayed_work() and queue_delayed_work() sequence. This guarantees that items currently marked as pending won't be scheduled an additional time, preventing a double release of resources which leads to the following crash: Oops: general protection fault, probably for non-canonical address 0xdead000000000122: 0000 [#1] SMP NOPTI Workqueue: cros_ec_ucsi.3.auto-con2 ucsi_poll_worker RIP: 0010:ucsi_poll_worker+0x65/0x1e0 Call Trace: process_scheduled_works+0x218/0x6d0 worker_thread+0x188/0x3f0 __cfi_worker_thread+0x10/0x10 kthread+0x226/0x2a0 To ensure these rules are applied identically across both the normal teardown and the ucsi_init() error paths, consolidate the cleanup logic into a new helper, ucsi_unregister_port(). Cc: stable@vger.kernel.org Fixes: b9aa02ca39a4 ("usb: typec: ucsi: Add polling mechanism for partner tasks like alt mode checking") Fixes: b13abcb7ddd8 ("usb: typec: ucsi: Fix NULL pointer access") Fixes: fac4b8633fd6 ("usb: ucsi: Ensure connector delayed work items are flushed") Signed-off-by: Andrei Kuchynski --- drivers/usb/typec/ucsi/ucsi.c | 82 +++++++++++++++++------------------ 1 file changed, 39 insertions(+), 43 deletions(-) diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c index 92166a3725b16..d9668ed7c80ea 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1845,6 +1845,42 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con) return ret; } +static void ucsi_unregister_port(struct ucsi_connector *con) +{ + struct ucsi_work *uwork; + + if (con->wq) { + mutex_lock(&con->lock); + ucsi_unregister_partner(con); + /* + * queue delayed items immediately so they can execute + * and free themselves before the wq is destroyed + */ + list_for_each_entry(uwork, &con->partner_tasks, node) { + if (cancel_delayed_work(&uwork->work)) + queue_delayed_work(con->wq, &uwork->work, 0); + } + mutex_unlock(&con->lock); + + destroy_workqueue(con->wq); + con->wq = NULL; + } else { + ucsi_unregister_partner(con); + } + + ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON); + ucsi_unregister_port_psy(con); + + usb_power_delivery_unregister_capabilities(con->port_sink_caps); + con->port_sink_caps = NULL; + usb_power_delivery_unregister_capabilities(con->port_source_caps); + con->port_source_caps = NULL; + usb_power_delivery_unregister(con->pd); + con->pd = NULL; + typec_unregister_port(con->port); + con->port = NULL; +} + static u64 ucsi_get_supported_notifications(struct ucsi *ucsi) { u16 features = ucsi->cap.features; @@ -1971,22 +2007,8 @@ static int ucsi_init(struct ucsi *ucsi) for (i = 0; i < ucsi->cap.num_connectors; i++) lockdep_unregister_key(&connector[i].lock_key); - for (con = connector; con->port; con++) { - if (con->wq) - destroy_workqueue(con->wq); - ucsi_unregister_partner(con); - ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON); - ucsi_unregister_port_psy(con); - - usb_power_delivery_unregister_capabilities(con->port_sink_caps); - con->port_sink_caps = NULL; - usb_power_delivery_unregister_capabilities(con->port_source_caps); - con->port_source_caps = NULL; - usb_power_delivery_unregister(con->pd); - con->pd = NULL; - typec_unregister_port(con->port); - con->port = NULL; - } + for (con = connector; con->port; con++) + ucsi_unregister_port(con); kfree(connector); err_reset: memset(&ucsi->cap, 0, sizeof(ucsi->cap)); @@ -2194,33 +2216,7 @@ void ucsi_unregister(struct ucsi *ucsi) for (i = 0; i < ucsi->cap.num_connectors; i++) { cancel_work_sync(&ucsi->connector[i].work); - - if (ucsi->connector[i].wq) { - struct ucsi_work *uwork; - - mutex_lock(&ucsi->connector[i].lock); - /* - * queue delayed items immediately so they can execute - * and free themselves before the wq is destroyed - */ - list_for_each_entry(uwork, &ucsi->connector[i].partner_tasks, node) - mod_delayed_work(ucsi->connector[i].wq, &uwork->work, 0); - mutex_unlock(&ucsi->connector[i].lock); - destroy_workqueue(ucsi->connector[i].wq); - } - - ucsi_unregister_partner(&ucsi->connector[i]); - ucsi_unregister_altmodes(&ucsi->connector[i], - UCSI_RECIPIENT_CON); - ucsi_unregister_port_psy(&ucsi->connector[i]); - - usb_power_delivery_unregister_capabilities(ucsi->connector[i].port_sink_caps); - ucsi->connector[i].port_sink_caps = NULL; - usb_power_delivery_unregister_capabilities(ucsi->connector[i].port_source_caps); - ucsi->connector[i].port_source_caps = NULL; - usb_power_delivery_unregister(ucsi->connector[i].pd); - ucsi->connector[i].pd = NULL; - typec_unregister_port(ucsi->connector[i].port); + ucsi_unregister_port(&ucsi->connector[i]); lockdep_unregister_key(&ucsi->connector[i].lock_key); } -- 2.55.0.rc2.803.g1fd1e6609c-goog