Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <RINjeKS0brZzIa6F-fgBKuiHrrcZB8zfTg_chbQIT3BRLqx-l9SmsxvV3LXx7upuctFCki33uAIhXNsM92YWTub8vbzSQHcJibhPkN5ijB8=@protonmail.com>
In-Reply-To: <RINjeKS0brZzIa6F-fgBKuiHrrcZB8zfTg_chbQIT3BRLqx-l9SmsxvV3LXx7upuctFCki33uAIhXNsM92YWTub8vbzSQHcJibhPkN5ijB8=@protonmail.com>
From:   Daniel Ogorchock <djogorchock@gmail.com>
Date:   Tue, 20 Sep 2022 18:02:33 -0400
Message-ID: <CAEVj2tn8byGn2RHmvYc77rv2BZkApW3yQ5qSDDzNGxhbygO2Ag@mail.gmail.com>
Subject: Re: [PATCH v2] HID: nintendo: check analog user calibration for plausibility
To:     Johnothan King <johnothanking@protonmail.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Jiri Kosina <jikos@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Sep 20, 2022 at 12:54 PM Johnothan King
<johnothanking@protonmail.com> wrote:
>
> 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 = center = max = 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
>
> Changes in v2:
>  - Move the plausibility check to joycon_read_stick_calibration() and
>    have that function return -EINVAL if the check fails.
>  - In the plausibility check, change >= to ==. hid_field_extract() never
>    returns a negative value, so a scenario involving min > center or
>    center > max is impossible.
>  - To reduce code duplication, move the code for setting default
>    calibration values into a single function called
>    joycon_use_default_calibration().
>
> 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 | 58 ++++++++++++++++++++++----------------
>  1 file changed, 33 insertions(+), 25 deletions(-)
>

Reviewed-by: Daniel J. Ogorchock <djogorchock@gmail.com>

Thanks for the fix. This seems like a good way around invalid calibration data.

-Daniel