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

Josh Poimboeuf posted 1 patch 1 month ago 
drivers/iio/imu/bmi160/bmi160_core.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
[PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()
Posted by Josh Poimboeuf 1 month ago 
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@arndb.de>
Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.fastmail.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 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;
 }
-- 
2.53.0
Re: [PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()
Posted by Nuno Sá 4 weeks, 1 day ago 
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@arndb.de>
> Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.fastmail.com
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---

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

>  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;
>  }
Re: [PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()
Posted by Jonathan Cameron 3 weeks, 3 days ago 
On Tue, 10 Mar 2026 14:57:19 +0000
Nuno Sá <noname.nuno@gmail.com> wrote:

> 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@arndb.de>
> > Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.fastmail.com
> > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> > ---  
> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan
Re: [PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()
Posted by Andy Shevchenko 4 weeks, 1 day ago 
On Mon, Mar 09, 2026 at 08:45:45PM -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.

Thanks!
Are you aware of this: https://bugzilla.kernel.org/show_bug.cgi?id=219192?
Perhaps also needs to be addressed? (I haven't checked if it's already done
or not.)

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko
Re: [PATCH v2] iio: imu: bmi160: Remove potential undefined behavior in bmi160_config_pin()
Posted by Josh Poimboeuf 4 weeks, 1 day ago 
On Tue, Mar 10, 2026 at 01:36:16PM +0200, Andy Shevchenko wrote:
> On Mon, Mar 09, 2026 at 08:45:45PM -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.
> 
> Thanks!
> Are you aware of this: https://bugzilla.kernel.org/show_bug.cgi?id=219192?
> Perhaps also needs to be addressed? (I haven't checked if it's already done
> or not.)

I'll be out the rest of this week, but I'll take a look when I get back.

> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

Thanks!

-- 
Josh

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