Re: REGRESSION: [PATCH] usb: typec: ucsi: Fix race condition and ordering in port unregistration
From: Andrei Kuchynski
Date: Thu Jul 16 2026 - 05:20:40 EST
On Thu, Jul 16, 2026 at 10:28 AM Borah, Chaitanya Kumar
<chaitanya.kumar.borah@xxxxxxxxx> wrote:
>
> Hello Andrei,
>
> On 7/7/2026 7:47 PM, Andrei Kuchynski wrote:
> > 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:
> > <IRQ>
> > __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:
> > <TASK>
> > 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().
>
>
> This seems to be causing regression in our linux-next CI. [1]
>
> <6>[ 18.008557] ------------[ cut here ]------------
> <4>[ 18.013166] DEBUG_LOCKS_WARN_ON(1)
> <4>[ 18.013167] WARNING: kernel/locking/lockdep.c:238 at
> __lock_acquire+0xa59/0x2750, CPU#1: kworker/u89:1/172
> ...
> <4>[ 18.159950] Hardware name: Intel Corporation Meteor Lake Client
> Platform/MTL-P DDR5 SODIMM SBS RVP, BIOS
> MTLPFWI1.R00.3471.D89.2401091901 01/09/2024
> <4>[ 18.173125] Workqueue: events_dfl_long ucsi_init_work [typec_ucsi]
> <4>[ 18.179257] RIP: 0010:__lock_acquire+0xa60/0x2750
> <4>[ 18.183927] Code: 44 8b 5d a8 85 c0 0f 84 98 fd ff ff 44 8b 35 07
> 0b 72 02 45 85 f6 0f 85 88 fd ff ff 48 8d 3d 27 25 73 02 48 c7 c6 1b 51
> 27 83 <67> 48 0f b9 3a 31 c0 44 8b 5d a8 44 8b 4d b0 e9 c6 f7 ff ff 31 d2
> ...
> <4>[ 18.263886] PKRU: 55555554
> <4>[ 18.266583] Call Trace:
> <4>[ 18.269014] <TASK>
> <4>[ 18.271110] ? mark_held_locks+0x46/0x90
> <4>[ 18.275007] lock_acquire+0xd9/0x2e0
> <4>[ 18.278562] ? ucsi_unregister_port+0x36/0x140 [typec_ucsi]
> <4>[ 18.284096] __mutex_lock+0xb2/0x1020
> <4>[ 18.287735] ? ucsi_unregister_port+0x36/0x140 [typec_ucsi]
> <4>[ 18.293265] ? ucsi_unregister_port+0x36/0x140 [typec_ucsi]
> <4>[ 18.298797] ? synchronize_rcu_expedited+0x2b2/0x300
> <4>[ 18.303724] ? __pfx_autoremove_wake_function+0x10/0x10
> <4>[ 18.308912] mutex_lock_nested+0x1b/0x30
> <4>[ 18.312806] ? mutex_lock_nested+0x1b/0x30
> <4>[ 18.316878] ucsi_unregister_port+0x36/0x140 [typec_ucsi]
> <4>[ 18.322238] ucsi_init_work+0x66d/0xc10 [typec_ucsi]
> <4>[ 18.327167] process_one_work+0x2ad/0x8b0
> <4>[ 18.331158] worker_thread+0x200/0x3f0
> <4>[ 18.334886] ? __pfx_worker_thread+0x10/0x10
> <4>[ 18.339128] kthread+0x10d/0x150
> <4>[ 18.342339] ? __pfx_kthread+0x10/0x10
> <4>[ 18.346067] ret_from_fork+0x3bd/0x470
> <4>[ 18.349795] ? __pfx_kthread+0x10/0x10
> <4>[ 18.353522] ret_from_fork_asm+0x1a/0x30
> <4>[ 18.357420] </TASK>
>
> Detailed log can be seen found in [2]
>
> We confirmed that reverting the patch solves the issue.
>
> Could you please check why the patch causes this regression and provide
> a fix if necessary?
>
> Regards
> Chaitanya
>
> [1] https://intel-gfx-ci.01.org/tree/linux-next/combined-alt.html?
> [2]
> https://intel-gfx-ci.01.org/tree/linux-next/next-20260714/bat-mtlp-9/boot0.txt
>
> -- Bisect Logs --
>
> git bisect start
> # status: waiting for both good and bad commits
> # good: [5f1b513690edf51727e6928b97705b6437f9a98e] Merge remote-tracking
> branch 'spi/for-7.3' into spi-next
> git bisect good 5f1b513690edf51727e6928b97705b6437f9a98e
> # status: waiting for bad commit, 1 good commit known
> # bad: [49362394dad7df66c274c867a271394c10ca2bb8] Add linux-next
> specific files for 20260713
> git bisect bad 49362394dad7df66c274c867a271394c10ca2bb8
> # bad: [dffddeb046466ed57038295bde28b42b7506a12b] Merge branch
> 'nand/next' of https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git
> git bisect bad dffddeb046466ed57038295bde28b42b7506a12b
> # bad: [d154d0766bf3fe830e1bf98fb2d8648294a4a8da] Merge branch
> 'for-next' of
> https://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap.git
> git bisect bad d154d0766bf3fe830e1bf98fb2d8648294a4a8da
> # bad: [671b0fd929bec9ebf863cb376baf9b9d1226a510] Merge branch 'master'
> of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git
> git bisect bad 671b0fd929bec9ebf863cb376baf9b9d1226a510
> # good: [f4fb100039e96211609dfc44fb24b9e4a8a0f2f9] Merge tag
> 's390-7.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
> git bisect good f4fb100039e96211609dfc44fb24b9e4a8a0f2f9
> # good: [c296d513e034df93ddb230ad1c7a118d6b58750c] Merge branch
> 'arm/fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git
> git bisect good c296d513e034df93ddb230ad1c7a118d6b58750c
> # good: [de53c0a584f08f31eb957f8c849a59fb33b27fa8] Merge branch 'for-rc'
> of https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git
> git bisect good de53c0a584f08f31eb957f8c849a59fb33b27fa8
> # bad: [a6969de5a038bc08a948ada52bd7199a8dfa6cec] Merge branch
> 'usb-linus' of
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
> git bisect bad a6969de5a038bc08a948ada52bd7199a8dfa6cec
> # good: [15eab2dd63a97587405ab6bfaad9728d5b35b5fe] Merge tag
> 'asoc-fix-v7.2-rc2' of
> https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
> git bisect good 15eab2dd63a97587405ab6bfaad9728d5b35b5fe
> # bad: [c2e819be6a5c7f34344926b4bd7e3dfca58cf48a] usb: gadget: printer:
> fix infinite loop in printer_read()
> git bisect bad c2e819be6a5c7f34344926b4bd7e3dfca58cf48a
> # good: [29a142d3e8b35ebc9e0bcc78f4bc26c9b6a9ac0b] USB: gadget:
> snps-udc: fix device name leak on probe failure
> git bisect good 29a142d3e8b35ebc9e0bcc78f4bc26c9b6a9ac0b
> # good: [1febec7e47cdcd01f43fb0211094e3010474666e] usb: gadget: f_ncm:
> validate datagram bounds in ncm_unwrap_ntb()
> git bisect good 1febec7e47cdcd01f43fb0211094e3010474666e
> # bad: [0583f2fbf8f86ae3a0ce054f96783dd83e65d9bb] usb: gadget: udc: bdc:
> free IRQ and drain func_wake_notify before teardown
> git bisect bad 0583f2fbf8f86ae3a0ce054f96783dd83e65d9bb
> # bad: [7aa7d4bf9d3fa9a6a47b640ad103ab433b7ff261] usb: typec: ucsi: Fix
> race condition and ordering in port unregistration
> git bisect bad 7aa7d4bf9d3fa9a6a47b640ad103ab433b7ff261
> # first bad commit: [7aa7d4bf9d3fa9a6a47b640ad103ab433b7ff261] usb:
> typec: ucsi: Fix race condition and ordering in port unregistration
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > 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 <akuchynski@xxxxxxxxxxxx>
> > ---
> > 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);
Hi Chaitanya,
Thank you for spotting this!
Could you verify if calling lockdep_unregister_key(&connector[i].lock_key)
after ucsi_unregister_port(con) resolves the issue?
for (con = connector; con->port; con++)
ucsi_unregister_port(con);
for (i = 0; i < ucsi->cap.num_connectors; i++)
lockdep_unregister_key(&connector[i].lock_key);
I will also try testing this on my side.
Thanks,
Andrei