Re: [PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()

[Nuno Sá]

On Mon, 2026-03-09 at 20:45 -0700, Josh Poimboeuf wrote:
> If 'pin' is not one of its expected values, the value of
> 'int_out_ctrl_shift' is undefined.  With UBSAN enabled, this causes
> Clang to generate undefined behavior, resulting in the following
> warning:
> 
>   drivers/iio/imu/bmi160/bmi160_core.o: warning: objtool: bmi160_setup_irq() falls through to next
> function __cfi_bmi160_core_runtime_resume()
> 
> Prevent the UB and improve error handling by returning an error if 'pin'
> has an unexpected value.
> 
> While at it, simplify the code a bit by moving the 'pin_name' assignment
> to the first switch statement.
> 
> Fixes: 895bf81e6bbf ("iio:bmi160: add drdy interrupt support")
> Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
> Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@xxxxxxxxxxxxxxxx
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---

Reviewed-by: Nuno Sá <nuno.sa@xxxxxxxxxx>

>  drivers/iio/imu/bmi160/bmi160_core.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi160/bmi160_core.c
> index 5f47708b4c5d..4abb83b75e2e 100644
> --- a/drivers/iio/imu/bmi160/bmi160_core.c
> +++ b/drivers/iio/imu/bmi160/bmi160_core.c
> @@ -573,12 +573,16 @@ static int bmi160_config_pin(struct regmap *regmap, enum bmi160_int_pin pin,
>  		int_out_ctrl_shift = BMI160_INT1_OUT_CTRL_SHIFT;
>  		int_latch_mask = BMI160_INT1_LATCH_MASK;
>  		int_map_mask = BMI160_INT1_MAP_DRDY_EN;
> +		pin_name = "INT1";
>  		break;
>  	case BMI160_PIN_INT2:
>  		int_out_ctrl_shift = BMI160_INT2_OUT_CTRL_SHIFT;
>  		int_latch_mask = BMI160_INT2_LATCH_MASK;
>  		int_map_mask = BMI160_INT2_MAP_DRDY_EN;
> +		pin_name = "INT2";
>  		break;
> +	default:
> +		return -EINVAL;
>  	}
>  	int_out_ctrl_mask = BMI160_INT_OUT_CTRL_MASK << int_out_ctrl_shift;
>  
> @@ -612,17 +616,8 @@ static int bmi160_config_pin(struct regmap *regmap, enum bmi160_int_pin pin,
>  	ret = bmi160_write_conf_reg(regmap, BMI160_REG_INT_MAP,
>  				    int_map_mask, int_map_mask,
>  				    write_usleep);
> -	if (ret) {
> -		switch (pin) {
> -		case BMI160_PIN_INT1:
> -			pin_name = "INT1";
> -			break;
> -		case BMI160_PIN_INT2:
> -			pin_name = "INT2";
> -			break;
> -		}
> +	if (ret)
>  		dev_err(dev, "Failed to configure %s IRQ pin", pin_name);
> -	}
>  
>  	return ret;
>  }