Re: [PATCH] iio: imu: bno055: uninitialized variable bug in bno055_trigger_handler()

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 14 Oct 2022 12:39:52 +0300
Dan Carpenter <dan.carpenter@oracle.com> wrote:

> This bug is basically harmless, although it will trigger a runtime warning
> if you use KMSan.  On the first iteration through the loop, the
> "best_delta" variable is uninitialized so re-order the condition to
> prevent reading uninitialized memory.
> 
> Fixes: 4aefe1c2bd0c ("iio: imu: add Bosch Sensortec BNO055 core driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

You reported this a while back along with a second issue (false positive)
with hwval.

I posted a patch fixing both 
https://lore.kernel.org/linux-iio/20221002145324.3776484-1-jic23@kernel.org/

I don't really care which patch goes in, but curious to reasoning to not also
deal with the hwval warning here?

Jonathan

> ---
>  drivers/iio/imu/bno055/bno055.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/imu/bno055/bno055.c b/drivers/iio/imu/bno055/bno055.c
> index 307557a609e3..52744dd98e65 100644
> --- a/drivers/iio/imu/bno055/bno055.c
> +++ b/drivers/iio/imu/bno055/bno055.c
> @@ -632,7 +632,7 @@ static int bno055_set_regmask(struct bno055_priv *priv, int val, int val2,
>  			return -EINVAL;
>  		}
>  		delta = abs(tbl_val - req_val);
> -		if (delta < best_delta || first) {
> +		if (first || delta < best_delta) {
>  			best_delta = delta;
>  			hwval = i;
>  			first = false;