Re: [PATCH v3] iio: light: Add check for array bounds in veml6075_read_int_time_ms

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 20 Feb 2025 17:34:36 +0000
Karan Sanghavi <karansanghvi98@gmail.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@gmail.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.

>  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)