linux-kernel - Re: [PATCH] iio: adc: palmas: fix off by one bugs

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Date:   Mon, 1 May 2023 16:06:09 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Patrik Dahlström <risca@...akolonin.se>
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] iio: adc: palmas: fix off by one bugs

On Sat, 29 Apr 2023 22:25:38 +0200
Patrik Dahlström <risca@...akolonin.se> wrote:

> On Sun, Apr 23, 2023 at 02:11:24PM +0100, Jonathan Cameron wrote:
> > On Fri, 21 Apr 2023 13:41:56 +0300
> > Dan Carpenter <dan.carpenter@...aro.org> wrote:
> >   
> > > Valid values for "adc_chan" are zero to (PALMAS_ADC_CH_MAX - 1).
> > > Smatch detects some buffer overflows caused by this:
> > > drivers/iio/adc/palmas_gpadc.c:721 palmas_gpadc_read_event_value() error: buffer overflow 'adc->thresholds' 16 <= 16
> > > drivers/iio/adc/palmas_gpadc.c:758 palmas_gpadc_write_event_value() error: buffer overflow 'adc->thresholds' 16 <= 16
> > > 
> > > The effect of this bug in other functions is more complicated but
> > > obviously we should fix all of them.
> > > 
> > > Fixes: a99544c6c883 ("iio: adc: palmas: add support for iio threshold events")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>  
> > 
> > Looks good to me.  Slight shuffle at the moment will delay me applying this.
> > 
> > I'll wait for Linus to pick up Greg's pull request then rebase my fixes branch
> > on top of that.  Otherwise I make a mess of linux-next ordering and things might
> > blow up.
> > 
> > In meantime, Patrik, please take a look.  
> 
> Sorry for the long delay.
> 
> The changes look good to me. I've checked all other uses of adc_chan in the
> code and they all seem to be guarded by the checks below.
> 
> Best regards
> Patrik
> 
My tree has now advanced appropriately.

Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan

> > 
> > Jonathan
> >   
> > > ---
> > > ---
> > >  drivers/iio/adc/palmas_gpadc.c | 10 +++++-----
> > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/iio/adc/palmas_gpadc.c b/drivers/iio/adc/palmas_gpadc.c
> > > index c1c439215aeb..7dfc9c927a23 100644
> > > --- a/drivers/iio/adc/palmas_gpadc.c
> > > +++ b/drivers/iio/adc/palmas_gpadc.c
> > > @@ -547,7 +547,7 @@ static int palmas_gpadc_read_raw(struct iio_dev *indio_dev,
> > >  	int adc_chan = chan->channel;
> > >  	int ret = 0;
> > >  
> > > -	if (adc_chan > PALMAS_ADC_CH_MAX)
> > > +	if (adc_chan >= PALMAS_ADC_CH_MAX)
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&adc->lock);
> > > @@ -595,7 +595,7 @@ static int palmas_gpadc_read_event_config(struct iio_dev *indio_dev,
> > >  	int adc_chan = chan->channel;
> > >  	int ret = 0;
> > >  
> > > -	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > > +	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&adc->lock);
> > > @@ -684,7 +684,7 @@ static int palmas_gpadc_write_event_config(struct iio_dev *indio_dev,
> > >  	int adc_chan = chan->channel;
> > >  	int ret;
> > >  
> > > -	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > > +	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&adc->lock);
> > > @@ -710,7 +710,7 @@ static int palmas_gpadc_read_event_value(struct iio_dev *indio_dev,
> > >  	int adc_chan = chan->channel;
> > >  	int ret;
> > >  
> > > -	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > > +	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&adc->lock);
> > > @@ -744,7 +744,7 @@ static int palmas_gpadc_write_event_value(struct iio_dev *indio_dev,
> > >  	int old;
> > >  	int ret;
> > >  
> > > -	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > > +	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&adc->lock);  
> >