[PATCH] Input: max77693-haptic - fix potential overflow

[PATCH] Input: max77693-haptic - fix potential overflow

[Dmitry Torokhov]

Expression haptic->pwm_dev->period * haptic->magnitude is of type 'unsigned
int' and may overflow. We need to convert one of the operands to u64 before
multiplying, instead of casting result (potentially overflown) to u64.

Reported by Coverity: CID 1248753

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/misc/max77693-haptic.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/input/misc/max77693-haptic.c b/drivers/input/misc/max77693-haptic.c
index 7b1fde9..ef6a9d6 100644
--- a/drivers/input/misc/max77693-haptic.c
+++ b/drivers/input/misc/max77693-haptic.c
@@ -194,7 +194,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
 				       struct ff_effect *effect)
 {
 	struct max77693_haptic *haptic = input_get_drvdata(dev);
-	uint64_t period_mag_multi;
+	u64 period_mag_multi;
 
 	haptic->magnitude = effect->u.rumble.strong_magnitude;
 	if (!haptic->magnitude)
@@ -205,8 +205,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
 	 * The formula to convert magnitude to pwm_duty as follows:
 	 * - pwm_duty = (magnitude * pwm_period) / MAX_MAGNITUDE(0xFFFF)
 	 */
-	period_mag_multi = (int64_t)(haptic->pwm_dev->period *
-						haptic->magnitude);
+	period_mag_multi = (u64)haptic->pwm_dev->period * haptic->magnitude;
 	haptic->pwm_duty = (unsigned int)(period_mag_multi >>
 						MAX_MAGNITUDE_SHIFT);
 
-- 
2.1.0.rc2.206.gedb03e5


-- 
Dmitry

Re: [PATCH] Input: max77693-haptic - fix potential overflow

[Jaewon Kim]

Hi Dmitry,

2014년 10월 29일 01:43에 Dmitry Torokhov 이(가) 쓴 글:
> Expression haptic->pwm_dev->period * haptic->magnitude is of type 'unsigned
> int' and may overflow. We need to convert one of the operands to u64 before
> multiplying, instead of casting result (potentially overflown) to u64.
>
> Reported by Coverity: CID 1248753
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>   drivers/input/misc/max77693-haptic.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/misc/max77693-haptic.c b/drivers/input/misc/max77693-haptic.c
> index 7b1fde9..ef6a9d6 100644
> --- a/drivers/input/misc/max77693-haptic.c
> +++ b/drivers/input/misc/max77693-haptic.c
> @@ -194,7 +194,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
>   				       struct ff_effect *effect)
>   {
>   	struct max77693_haptic *haptic = input_get_drvdata(dev);
> -	uint64_t period_mag_multi;
> +	u64 period_mag_multi;
>   
>   	haptic->magnitude = effect->u.rumble.strong_magnitude;
>   	if (!haptic->magnitude)
> @@ -205,8 +205,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
>   	 * The formula to convert magnitude to pwm_duty as follows:
>   	 * - pwm_duty = (magnitude * pwm_period) / MAX_MAGNITUDE(0xFFFF)
>   	 */
> -	period_mag_multi = (int64_t)(haptic->pwm_dev->period *
> -						haptic->magnitude);
> +	period_mag_multi = (u64)haptic->pwm_dev->period * haptic->magnitude;
>   	haptic->pwm_duty = (unsigned int)(period_mag_multi >>
>   						MAX_MAGNITUDE_SHIFT);
>   


There was casting miss in multiplying.
Thanks.

Acked-by : Jaewon Kim <jaewon02.kim@samsung.com>

Re: [PATCH] Input: max77693-haptic - fix potential overflow

[Chanwoo Choi]

On 10/29/2014 01:43 AM, Dmitry Torokhov wrote:
> Expression haptic->pwm_dev->period * haptic->magnitude is of type 'unsigned
> int' and may overflow. We need to convert one of the operands to u64 before
> multiplying, instead of casting result (potentially overflown) to u64.
> 
> Reported by Coverity: CID 1248753
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  drivers/input/misc/max77693-haptic.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/misc/max77693-haptic.c b/drivers/input/misc/max77693-haptic.c
> index 7b1fde9..ef6a9d6 100644
> --- a/drivers/input/misc/max77693-haptic.c
> +++ b/drivers/input/misc/max77693-haptic.c
> @@ -194,7 +194,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
>  				       struct ff_effect *effect)
>  {
>  	struct max77693_haptic *haptic = input_get_drvdata(dev);
> -	uint64_t period_mag_multi;
> +	u64 period_mag_multi;
>  
>  	haptic->magnitude = effect->u.rumble.strong_magnitude;
>  	if (!haptic->magnitude)
> @@ -205,8 +205,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
>  	 * The formula to convert magnitude to pwm_duty as follows:
>  	 * - pwm_duty = (magnitude * pwm_period) / MAX_MAGNITUDE(0xFFFF)
>  	 */
> -	period_mag_multi = (int64_t)(haptic->pwm_dev->period *
> -						haptic->magnitude);
> +	period_mag_multi = (u64)haptic->pwm_dev->period * haptic->magnitude;
>  	haptic->pwm_duty = (unsigned int)(period_mag_multi >>
>  						MAX_MAGNITUDE_SHIFT);
>  
> 

Looks good to me.

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

Thanks,
Chanwoo Choi