linux-kernel - Re: [PATCH v1] ASoC: rt5640: Fix NULL dereference on module unload

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Date:   Mon, 30 Dec 2019 22:37:03 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Bard Liao <bardliao@...ltek.com>,
        Oder Chiou <oder_chiou@...ltek.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Takashi Iwai <tiwai@...e.com>, linux-tegra@...r.kernel.org,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] ASoC: rt5640: Fix NULL dereference on module unload

30.12.2019 10:11, Takashi Iwai пишет:
> On Sun, 29 Dec 2019 16:04:54 +0100,
> Dmitry Osipenko wrote:
>>
>> The rt5640->jack is NULL if jack is already disabled at the time of
>> driver's module unloading.
>>
>>  Unable to handle kernel NULL pointer dereference at virtual address 00000024
>>  ...
>>  (rt5640_set_jack [snd_soc_rt5640]) from [<bf86f7ed>] (snd_soc_component_set_jack+0x11/0x1c [snd_soc_core])
>>  (snd_soc_component_set_jack [snd_soc_core]) from [<bf8675cf>] (soc_remove_component+0x1b/0x54 [snd_soc_core])
>>  (soc_remove_component [snd_soc_core]) from [<bf868859>] (soc_cleanup_card_resources+0xad/0x1cc [snd_soc_core])
>>  (soc_cleanup_card_resources [snd_soc_core]) from [<bf86945f>] (snd_soc_unregister_card+0x47/0x78 [snd_soc_core])
>>  (snd_soc_unregister_card [snd_soc_core]) from [<bf8b4013>] (tegra_rt5640_remove+0x13/0x1c [snd_soc_tegra_rt5640])
>>  (tegra_rt5640_remove [snd_soc_tegra_rt5640]) from [<c0516d2f>] (platform_drv_remove+0x17/0x24)
>>  (platform_drv_remove) from [<c0515aed>] (device_release_driver_internal+0x95/0x114)
>>  (device_release_driver_internal) from [<c0515bd9>] (driver_detach+0x4d/0x90)
>>  (driver_detach) from [<c0514d59>] (bus_remove_driver+0x31/0x70)
>>  (bus_remove_driver) from [<bf8b4215>] (tegra_rt5640_driver_exit+0x9/0xdf4 [snd_soc_tegra_rt5640])
>>  (tegra_rt5640_driver_exit [snd_soc_tegra_rt5640]) from [<c019336f>] (sys_delete_module+0xe7/0x184)
>>  (sys_delete_module) from [<c0101001>] (ret_fast_syscall+0x1/0x28)
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  sound/soc/codecs/rt5640.c | 22 ++++++++++++++--------
>>  1 file changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/sound/soc/codecs/rt5640.c b/sound/soc/codecs/rt5640.c
>> index adbae1f36a8a..b245c44cafbc 100644
>> --- a/sound/soc/codecs/rt5640.c
>> +++ b/sound/soc/codecs/rt5640.c
>> @@ -2432,16 +2432,22 @@ static void rt5640_disable_jack_detect(struct snd_soc_component *component)
>>  {
>>  	struct rt5640_priv *rt5640 = snd_soc_component_get_drvdata(component);
>>  
>> -	disable_irq(rt5640->irq);
>> -	rt5640_cancel_work(rt5640);
>> +	/*
>> +	 * soc_remove_component() force-disables jack and thus rt5640->jack
>> +	 * could be NULL at the time of driver's module unloading.
>> +	 */
>> +	if (rt5640->jack) {
>> +		disable_irq(rt5640->irq);
>> +		rt5640_cancel_work(rt5640);
>>  
>> -	if (rt5640->jack->status & SND_JACK_MICROPHONE) {
>> -		rt5640_disable_micbias1_ovcd_irq(component);
>> -		rt5640_disable_micbias1_for_ovcd(component);
>> -		snd_soc_jack_report(rt5640->jack, 0, SND_JACK_BTN_0);
>> -	}
>> +		if (rt5640->jack->status & SND_JACK_MICROPHONE) {
>> +			rt5640_disable_micbias1_ovcd_irq(component);
>> +			rt5640_disable_micbias1_for_ovcd(component);
>> +			snd_soc_jack_report(rt5640->jack, 0, SND_JACK_BTN_0);
>> +		}
>>  
>> -	rt5640->jack = NULL;
>> +		rt5640->jack = NULL;
>> +	}
>>  }
> 
> I guess it's simpler just returning if rt5640->jack is already NULL.
> 
> --- a/sound/soc/codecs/rt5640.c
> +++ b/sound/soc/codecs/rt5640.c
> @@ -2432,6 +2432,10 @@ static void rt5640_disable_jack_detect(struct snd_soc_component *component)
>  {
>  	struct rt5640_priv *rt5640 = snd_soc_component_get_drvdata(component);
>  
> +	/* already disabled? */
> +	if (!rt5640->jack)
> +		return;
> +
>  	disable_irq(rt5640->irq);
>  	rt5640_cancel_work(rt5640);
>  
> 
> thanks,
> 
> Takashi
> 

Okay, I'll make v2.