linux-kernel - Re: [PATCH v3] iio: light: Add check for array bounds in veml6075_read_int_time

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Message-ID: <20250222164519.45c48a52@jic23-huawei>
Date: Sat, 22 Feb 2025 16:45:19 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Karan Sanghavi <karansanghvi98@...il.com>
Cc: Javier Carrasco <javier.carrasco.cruz@...il.com>, Lars-Peter Clausen
 <lars@...afoo.de>, linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v3] iio: light: Add check for array bounds in
 veml6075_read_int_time_ms

On Sat, 22 Feb 2025 16:43:37 +0000
Jonathan Cameron <jic23@...nel.org> wrote:

> On Thu, 20 Feb 2025 17:34:36 +0000
> Karan Sanghavi <karansanghvi98@...il.com> wrote:
> 
> > The array contains only 5 elements, but the index calculated by
> > veml6075_read_int_time_index can range from 0 to 7,
> > which could lead to out-of-bounds access. The check prevents this issue.
> > 
> > Coverity Issue
> > CID 1574309: (#1 of 1): Out-of-bounds read (OVERRUN)
> > overrun-local: Overrunning array veml6075_it_ms of 5 4-byte
> > elements at element index 7 (byte offset 31) using
> > index int_index (which evaluates to 7)
> > 
> > Fixes: 3b82f43238ae ("iio: light: add VEML6075 UVA and UVB light sensor driver")
> > Signed-off-by: Karan Sanghavi <karansanghvi98@...il.com>
> > ---  
> Superficially this looks hardening against malicious or broken hardware.
> That is fine to add, but not worth backporting or (in my opinion) adding a fixes
> tag.
Ah I see Javier asked for the fixes tag.  Ok.  Maybe just add a note that
the hardware is not expected to return such an out of bounds value.

That will help me to remember we don't need to rush this one upstream!

Jonathan

> 
> >  drivers/iio/light/veml6075.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/light/veml6075.c b/drivers/iio/light/veml6075.c
> > index 05d4c0e9015d..5dd951f6e989 100644
> > --- a/drivers/iio/light/veml6075.c
> > +++ b/drivers/iio/light/veml6075.c
> > @@ -201,7 +201,12 @@ static int veml6075_read_int_time_index(struct veml6075_data *data)
> >  	if (ret < 0)
> >  		return ret;
> >  
> > -	return FIELD_GET(VEML6075_CONF_IT, conf);
> > +	int int_index = FIELD_GET(VEML6075_CONF_IT, conf);
> > +
> > +	if (int_index >= ARRAY_SIZE(veml6075_it_ms))
> > +		return -EINVAL;
> > +
> > +	return int_index;
> >  }
> >  
> >  static int veml6075_read_int_time_ms(struct veml6075_data *data, int *val)  
>