Re: [PATCH 10/11] iio: light: as73211: fix information leak in triggered buffer

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 25 Nov 2024 22:16:18 +0100
Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:

> The 'scan' local struct is used to push data to userspace from a
> triggered buffer, but it leaves the first channel uninitialized if
> AS73211_SCAN_MASK_ALL is not set. That is used to optimize color channel
> readings.
> 
> Set the temperature channel to zero if only color channels are
> relevant to avoid pushing uninitialized information to userspace.
> 
> Cc: stable@vger.kernel.org
> Fixes: 403e5586b52e ("iio: light: as73211: New driver")
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Huh.

If the temperature channel is turned off the data should shift. So should be read
into scan.chan[0] and [1] and [2], but not [3].

Not skipping [0] as here.

So this code path currently doesn't work as far as I can tell.

Jonathan

> ---
>  drivers/iio/light/as73211.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c
> index be0068081ebb..99679b686146 100644
> --- a/drivers/iio/light/as73211.c
> +++ b/drivers/iio/light/as73211.c
> @@ -675,6 +675,9 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
>  				(char *)&scan.chan[1], 3 * sizeof(scan.chan[1]));
>  		if (ret < 0)
>  			goto done;
> +
> +		/* Avoid leaking uninitialized data */
> +		scan.chan[0] = 0;
>  	}
>  
>  	if (data_result) {
>