linux-kernel - Re: [PATCH 2/2] ASoC: Add BUG() assertion if max98095_get_bq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 29 Sep 2011 09:59:13 +0800
From:	Dave Young <hidave.darkstar@...il.com>
To:	Ryan Mallon <rmallon@...il.com>
Cc:	Axel Lin <axel.lin@...il.com>, linux-kernel@...r.kernel.org,
	Liam Girdwood <lrg@...com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	alsa-devel@...a-project.org,
	Peter Hsiang <peter.hsiang@...im-ic.com>,
	Jesse Marroquin <jesse.marroquin@...im-ic.com>
Subject: Re: [PATCH 2/2] ASoC: Add BUG() assertion if max98095_get_bq_channel
 returns -EINVAL

On Thu, Sep 29, 2011 at 9:52 AM, Ryan Mallon <rmallon@...il.com> wrote:
> On 29/09/11 11:35, Dave Young wrote:
>
>> On Thu, Sep 29, 2011 at 7:19 AM, Ryan Mallon <rmallon@...il.com> wrote:
>>> On 29/09/11 00:02, Axel Lin wrote:
>>>> The callers use the return value of max98095_get_bq_channel as array index to
>>>> access max98095->dai[] array.
>>>> Add BUG() assertion for out of bound access of max98095->dai[] array.
>>>
>>> Same here, fix the problem in the callers.
>>>
>>> ----
>>> Check the return value of max98095_get_bq_channel in the callers and
>>> propagate any errors up. Remove the BUG_ON(channel > 1) since
>>> max98095_get_bq_channel never returns a value larger than 1.
>>>
>>> Signed-off-by: Ryan Mallon <rmallon@...il.com>
>>> ---
>>>
>>> diff --git a/sound/soc/codecs/max98095.c b/sound/soc/codecs/max98095.c
>>> index 668434d..55eccea 100644
>>> --- a/sound/soc/codecs/max98095.c
>>> +++ b/sound/soc/codecs/max98095.c
>>> @@ -2014,7 +2014,8 @@ static int max98095_put_bq_enum(struct snd_kcontrol *kcontrol,
>>>        int fs, best, best_val, i;
>>>        int regmask, regsave;
>>>
>>> -       BUG_ON(channel > 1);
>>> +       if (channel < 0)
>>> +               return channel;
>>
>> If use BUG() happens in  max98095_get_bq_channel, it will not return here?
>
>
> Not quite sure what you mean?

I means if Axel Lin's patch applied, and CONFIG_BUG is on, it will
panic firstly the if condition will be never entered.

>
> If CONFIG_BUG was not enabled for the original version, then it would
> not return at the BUG_ON and would either crash or cause odd behaviour
> if it tried to index channel as -1.
>
> My patch is removing the BUG_ON and replacing it with a proper check and
> return. It doesn't need to check > 1 since max98095_get_bq_channel never
> returns that.
>
> My understanding is that device drivers, in general, should not call
> BUG. BUG is for unrecoverable errors which leave the kernel in some
> unstable state. Here we can just return an error code.

Agree

>
> ~Ryan
>
>>
>>>
>>>        if (!pdata || !max98095->bq_textcnt)
>>>                return 0;
>>> @@ -2069,6 +2070,9 @@ static int max98095_get_bq_enum(struct snd_kcontrol *kcontrol,
>>>        int channel = max98095_get_bq_channel(kcontrol->id.name);
>>>        struct max98095_cdata *cdata;
>>>
>>> +       if (channel < 0)
>>> +               return channel;
>>> +
>>>        cdata = &max98095->dai[channel];
>>>        ucontrol->value.enumerated.item[0] = cdata->bq_sel;
>>>
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>>> the body of a message to majordomo@...r.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> Please read the FAQ at  http://www.tux.org/lkml/
>>>
>>
>>
>>
>
>
>



-- 
Regards
Dave
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/