FAILED: patch "[PATCH] HID: multitouch: stop the release timer from being rearmed on" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 5acb2dace582f061aab5e14c399ac9480315f44b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026100302-ecosystem-ozone-ce3b@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5acb2dace582f061aab5e14c399ac9480315f44b Mon Sep 17 00:00:00 2001
From: Aldo Ariel Panzardo <[email protected]>
Date: Wed, 23 Sep 2026 08:58:47 -0300
Subject: [PATCH] HID: multitouch: stop the release timer from being rearmed on
remove

mt_remove() quiesces the sticky-finger timer before stopping the hardware:

    timer_delete_sync(&td->release_timer);

    sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
    hid_hw_stop(hdev);

timer_delete_sync() waits for a running callback and dequeues the timer, but it does not stop the timer from being armed again. The transport is still delivering reports at that point, and the report path rearms it:

    if (app->quirks & MT_QUIRK_STICKY_FINGERS) {
        if (td->mt_io_flags & MT_IO_SLOTS_MASK)
            mod_timer(&td->release_timer,
                      jiffies + msecs_to_jiffies(100));

A report that arrives after timer_delete_sync() has returned therefore leaves the timer queued. td is allocated with devm_kzalloc() against hdev->dev, so it is freed when the driver is unbound, after mt_remove() returns. When the timer fires afterwards, mt_expired_timeout() dereferences the freed td:

    struct mt_device *td = timer_container_of(td, t, release_timer);
    struct hid_device *hdev = td->hdev;

    if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))

Simply moving the teardown after hid_hw_stop() does not fix this on its own, because mt_expired_timeout() calls mt_release_contacts(), which walks hdev->inputs; the timer still has to be quiesced before hid_hw_stop() tears the input devices down.

Use timer_shutdown_sync() instead, which additionally makes any later mod_timer() a no-op, so neither ordering constraint has to be traded off against the other. This is the final-teardown pattern the function was introduced for, and hid-wiimote already uses it for the same reason.

index ab4ac261fe76..4e19a0c4d238 100644
@@ -2249,7 +2249,7 @@ static void mt_remove(struct hid_device *hdev)
 {
 	struct mt_device *td = hid_get_drvdata(hdev);
 
-	timer_delete_sync(&td->release_timer);
+	timer_shutdown_sync(&td->release_timer);
 
 	sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
 	hid_hw_stop(hdev);