HID: multitouch: stop the release timer from being rearmed on remove

Summary

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

Timeline

1. Oct 18, 2026, 3:51 PM UTCCVE published
2. Oct 21, 2026, 12:57 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 4f4001bc76fd1a138a501fbd3d68cce72cbf96ce · fixed in 3776f34fbce990af45978f1628d2e1adc0d67d0f; From 4f4001bc76fd1a138a501fbd3d68cce72cbf96ce · fixed in 1f1bd9a3117f082eb891c0986c4f0e04cd974c9a; From 4f4001bc76fd1a138a501fbd3d68cce72cbf96ce · fixed in 0c19a6c1d25fd5ed66d1f80dc6f6e56cc1f0a787; From 4f4001bc76fd1a138a501fbd3d68cce72cbf96ce · fixed in a0125ca86e405b8a704e96157a6c10ca51087652; From 4f4001bc76fd1a138a501fbd3d68cce72cbf96ce · fixed in 5acb2dace582f061aab5e14c399ac9480315f44b

• Linux Linux

  4.13

• KernelLinux

  From 4.13.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.113; From 6.13.0 · fixed in 6.18.56; From 6.19.0 · fixed in 7.2.10

References 5