Messages in this thread | | | Date | Thu, 29 Sep 2011 10:06:00 +0800 | Subject | Re: [PATCH 2/2] ASoC: Add BUG() assertion if max98095_get_bq_channel returns -EINVAL | From | Dave Young <> |
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On Thu, Sep 29, 2011 at 10:01 AM, Ryan Mallon <rmallon@gmail.com> wrote: > On 29/09/11 11:59, Dave Young wrote: > >> On Thu, Sep 29, 2011 at 9:52 AM, Ryan Mallon <rmallon@gmail.com> wrote: >>> On 29/09/11 11:35, Dave Young wrote: >>> >>>> On Thu, Sep 29, 2011 at 7:19 AM, Ryan Mallon <rmallon@gmail.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@gmail.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. > > My patch is a replacement for Axel's patch, not on top of it. For Axel's > patch it would panic if channel was less than zero if CONFIG_BUG was > enabled, but would still have undefined behaviour if CONFIG_BUG was not > enabled.
So that's good, thanks
> > ~Ryan > >>> >>> 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@vger.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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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