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Date:   Wed, 14 Sep 2022 07:43:50 +0000
To:     "Daniel J. Ogorchock" <djogorchock@gmail.com>,
        Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
From:   Johnothan King <johnothanking@protonmail.com>
Subject: [PATCH] HID: nintendo: check analog user calibration for plausibility
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Arne Wendt writes:
  Cheap clone controllers may (falsely) report as having a user
  calibration for the analog sticks in place, but return
  wrong/impossible values for the actual calibration data.
  In the present case at mine, the controller reports having a
  user calibration in place and successfully executes the read
  commands. The reported user calibration however is
  min =3D center =3D max =3D 0.

  This pull request addresses problems of this kind by checking the
  provided user calibration-data for plausibility (min < center < max)
  and falling back to the default values if implausible.

I'll note that I was experiencing a crash because of this bug when using
the GuliKit KingKong 2 controller. The crash manifests as a divide by
zero error in the kernel logs:
kernel: divide error: 0000 [#1] PREEMPT SMP NOPTI

Link: https://github.com/nicman23/dkms-hid-nintendo/pull/25
Link: https://github.com/DanielOgorchock/linux/issues/36
Co-authored-by: Arne Wendt <arne.wendt@tuhh.de>
Signed-off-by: Johnothan King <johnothanking@protonmail.com>
---
 drivers/hid/hid-nintendo.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index 6028af3c3aae..7f287f6a75f5 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -793,7 +793,17 @@ static int joycon_request_calibration(struct joycon_ct=
lr *ctlr)
 =09=09=09=09=09    &ctlr->left_stick_cal_x,
 =09=09=09=09=09    &ctlr->left_stick_cal_y,
 =09=09=09=09=09    true);
-=09if (ret) {
+
+=09/*
+=09 * Check whether read succeeded and perform plausibility check
+=09 * for retrieved values.
+=09 */
+=09if (ret ||
+=09=09ctlr->left_stick_cal_x.min >=3D ctlr->left_stick_cal_x.center ||
+=09=09ctlr->left_stick_cal_x.center >=3D ctlr->left_stick_cal_x.max ||
+=09=09ctlr->left_stick_cal_y.min >=3D ctlr->left_stick_cal_y.center ||
+=09=09ctlr->left_stick_cal_y.center >=3D ctlr->left_stick_cal_y.max
+=09) {
 =09=09hid_warn(ctlr->hdev,
 =09=09=09 "Failed to read left stick cal, using dflts; e=3D%d\n",
 =09=09=09 ret);
@@ -812,7 +822,17 @@ static int joycon_request_calibration(struct joycon_ct=
lr *ctlr)
 =09=09=09=09=09    &ctlr->right_stick_cal_x,
 =09=09=09=09=09    &ctlr->right_stick_cal_y,
 =09=09=09=09=09    false);
-=09if (ret) {
+
+=09/*
+=09 * Check whether read succeeded and perform plausibility check
+=09 * for retrieved values.
+=09 */
+=09if (ret ||
+=09=09ctlr->right_stick_cal_x.min >=3D ctlr->right_stick_cal_x.center ||
+=09=09ctlr->right_stick_cal_x.center >=3D ctlr->right_stick_cal_x.max ||
+=09=09ctlr->right_stick_cal_y.min >=3D ctlr->right_stick_cal_y.center ||
+=09=09ctlr->right_stick_cal_y.center >=3D ctlr->right_stick_cal_y.max
+=09) {
 =09=09hid_warn(ctlr->hdev,
 =09=09=09 "Failed to read right stick cal, using dflts; e=3D%d\n",
 =09=09=09 ret);
--=20
2.37.3