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Subject: Re: [PATCH] Input: elants_i2c - Fix NULL dereference at probing
To:     Takashi Iwai <tiwai@suse.de>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
References: <20210526194301.28780-1-tiwai@suse.de>
 <YK6tZy3E/XZpOAbh@google.com>
 <b7fc167b-23c6-fd64-cfbf-dd16a90fbf63@gmail.com>
 <s5hmtsg8zmn.wl-tiwai@suse.de>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <85932641-4b41-1505-4bb6-077220f2835b@gmail.com>
Date:   Thu, 27 May 2021 22:01:21 +0300
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27.05.2021 09:22, Takashi Iwai пишет:
> On Wed, 26 May 2021 22:44:59 +0200,
> Dmitry Osipenko wrote:
>>
>> Hello all,
>>
>> 26.05.2021 23:19, Dmitry Torokhov пишет:
>>> Hi Takashi,
>>>
>>> On Wed, May 26, 2021 at 09:43:01PM +0200, Takashi Iwai wrote:
>>>> The recent change in elants_i2c driver to support more chips
>>>> introduced a regression leading to Oops at probing.  The driver reads
>>>> id->driver_data, but the id may be NULL depending on the device type
>>>> the driver gets bound.
>>>>
>>>> Add a NULL check and falls back to the default EKTH3500.
>>>
>>> Thank you for the patch. I think my preference would be to switch to
>>> device_get_match_data() and annotate the rest of the match tables with
>>> proper controller types.
>>
>> Doesn't a NULL mean that elants_i2c_id[] table fails to match the ACPI
>> device name? What is the name then?
> 
> I don't own the device, so we need to ask on (open)SUSE Bugzilla.

If we will know the name, then alternative fix could be to add the name
to the elants_i2c_id[]. To be honest, I thought that the ID should be
borrowed from elants_acpi_id[] for the ACPI devices, but this was a mistake.

>> This could be two patches:
>>   1 - trivial fix that can be backported easily
>>   2 - switch to device_get_match_data()
> 
> I guess 2 is easy enough to backport to 5.12.x.  Let's see.

Okay