[PATCH v5 0/2] HID: multitouch: fix use-after-free of haptic data on delayed input release

[Aldo Ariel Panzardo <qwe.aldo@gmail.com>]

Hi Benjamin,

Thanks for the feedback on v4.  Reworked as you asked -- devm_kzalloc
stays, a devm_add_action() handles teardown, and the try_module_get
reorder is now a separate patch.

Patch 1 moves try_module_get()/get_device() before input_ff_create()
so the old input_free error path (which returned ret == 0) goes away.

Patch 2 adds a devm_add_action() callback in hid_haptic_init() that
does all the resource teardown at unbind.  hid_haptic_destroy() just
sets ff->private = NULL so the subsequent kfree in input_ff_destroy
is harmless.  input_get_device() pins the input device for the
duration of the devres action.

Changes since v4:
  - keep devm_kzalloc, use devm_add_action (Benjamin)
  - split reorder into its own patch (Benjamin)
  - single-owner teardown -- destroy only NULLs ff->private,
    devm action owns workqueue drain + buffer frees + ref puts
  - input_get_device pins input_dev against concurrent release
  - workqueue drained before any pointer NULLs or frees
  - input_ff_destroy on devm_add_action failure
  - no hid-multitouch.c or hid-haptic.h changes

v4: https://lore.kernel.org/linux-input/20261009103333.2476105-1-qwe.aldo@gmail.com/
v3: https://lore.kernel.org/linux-input/20261009110509.2432308-1-qwe.aldo@gmail.com/
v1: https://lore.kernel.org/linux-input/20261009031207.3233206-1-qwe.aldo@gmail.com/

Aldo Ariel Panzardo (2):
  HID: haptic: reorder try_module_get/get_device before input_ff_create
  HID: multitouch: fix use-after-free of haptic data on delayed input
    release

 drivers/hid/hid-haptic.c | 87 ++++++++++++++++++++++++++++------------
 1 file changed, 62 insertions(+), 25 deletions(-)

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2.53.0