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

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Message-Id: <D7IJZ2639BOH.3KPFSYMOLZBGM@gmail.com>
Date: Mon, 03 Feb 2025 06:14:46 +0100
From: "Javier Carrasco" <javier.carrasco.cruz@...il.com>
To: "Javier Carrasco" <javier.carrasco.cruz@...il.com>, "Karan Sanghavi"
 <karansanghvi98@...il.com>, "Jonathan Cameron" <jic23@...nel.org>,
 "Lars-Peter Clausen" <lars@...afoo.de>
Cc: "Jonathan Cameron" <Jonathan.Cameron@...wei.com>,
 <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Shuah Khan"
 <skhan@...uxfoundation.org>
Subject: Re: [PATCH] iio: light: Add check for array bounds in
 veml6075_read_int_time_ms

On Sun Feb 2, 2025 at 6:09 PM CET, Javier Carrasco wrote:
> On Sun Feb 2, 2025 at 11:49 AM CET, Karan Sanghavi 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>
> > ---
> >  drivers/iio/light/veml6075.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/light/veml6075.c b/drivers/iio/light/veml6075.c
> > index 05d4c0e9015d..a892330582f4 100644
> > --- a/drivers/iio/light/veml6075.c
> > +++ b/drivers/iio/light/veml6075.c
> > @@ -210,7 +210,7 @@ static int veml6075_read_int_time_ms(struct veml6075_data *data, int *val)
> >
> >  	guard(mutex)(&data->lock);
> >  	int_index = veml6075_read_int_time_index(data);
> > -	if (int_index < 0)
> > +	if (int_index < 0 || int_index >= ARRAY_SIZE(veml6075_it_ms))
> >  		return int_index;
> >
> >  	*val = veml6075_it_ms[int_index];
> >
> > ---
> > base-commit: df4b2bbff898227db0c14264ac7edd634e79f755
> > change-id: 20250202-outofboundsread1573409-378997439be1
> >
> > Best regards,
>
>
> Hi Karan,
>
> Thanks for your patch. That could never happen because the device does
> not support those values: it only delivers values between 0 and 4 for
> that field because it does not support more integration times.
>
> Even though the check does not do anything in reality, it does not hurt
> either, and I would like to avoid future noise from coverity.
>
> Reviewed-by: Javier Carrasco <javier.carrasco.cruz@...il.com>

Second thought: you are not returning an error code, only a value
between 5 and 7. 5 and 6 are even valid return codes.

Please complete your patch to return a sensible error code.

Best regards,
Javier Carrasco