[PATCH v4 0/6] HID: wacom: guard against NULL input devices on successful probe

[Jinmo Yang <jinmo44.yang@gmail.com>]

When wacom_setup_{pen,touch,pad}_input_capabilities() returns -ENODEV,
the corresponding input pointer is set to NULL but probe still succeeds.
Subsequent irq handlers dereference those pointers unconditionally,
causing NULL-pointer dereferences reachable from a spoofed HID device.

This series adds per-function NULL guards across all affected handlers.

Changes in v4:
  - wacom_intuos_pad() now returns 2 for the normal path, 1 for the
    NULL-guard path; wacom_intuos_irq() applies "result - 1" uniformly,
    suppressing the spurious input_sync() the old "return 1" would
    trigger (Jason).
  - Added pen_input NULL guard at the top of wacom_intuos_irq() to
    protect its helpers wacom_intuos_inout() and
    wacom_intuos_general() (Jason).
  - Added pen_input NULL guard to wacom_bpt_pen() (Jason).

Changes in v3:
  - Fixed wacom_dtus_irq(): DTUSX is pen-only, so do not require
    pad_input for it (sashiko-bot).
  - Added patch 6: touch_input guards for wacom_intuos_pro2_bt_touch(),
    wacom_24hdt_irq(), and wacom_bamboo_pad_touch_event().

Changes in v2:
  - Restructured per Jason's review: per-function checks for dtus_irq,
    graphire_irq, and the Bamboo handlers.
  - wacom_intuos_pad() returns non-zero when pad_input is NULL so the
    report does not fall through to wacom_intuos_inout() (sashiko-bot).
  - wacom_intuos_bt_irq() guards both pen_input and pad_input (Jason).
  - Added dev_warn_once at every guard (Jason).
  - Dropped the cp2112 patch (Benjamin prefers Dmitry's series).

Jinmo Yang (6):
  HID: wacom: check the input device in the shared report helpers
  HID: wacom: check the input devices in the legacy irq handlers
  HID: wacom: add NULL input guards to wacom_intuos_irq() and its
    helpers
  HID: wacom: add NULL input guards to wacom_intuos_bt_irq()
  HID: wacom: add NULL input guards to Bamboo handlers
  HID: wacom: add NULL touch_input guards to remaining touch handlers

 drivers/hid/wacom_wac.c | 127 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 122 insertions(+), 5 deletions(-)

--
2.53.0