linux-kernel - Re: [PATCH RESEND] twl4030_charger: fix charging current out-of-bounds

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Message-ID: <20180930201642.GC23554@amd>
Date:   Sun, 30 Sep 2018 22:16:42 +0200
From:   Pavel Machek <pavel@....cz>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     sre@...nel.org, linux-pm@...r.kernel.org,
        linux-omap@...r.kernel.org,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] twl4030_charger: fix charging current
 out-of-bounds

On Mon 2018-09-17 07:20:35, Andreas Kemnade wrote:
> the charging current uses unsigned int variables, if we step back
> if the current is still low, we would run into negative which
> means setting the target to a huge value.
> Better add checks here.

Do you expect this to happen in practice? Too high current while
charging seems bad, right?

Cc: stable?
								Pavel

> Signed-off-by: Andreas Kemnade <andreas@...nade.info>
> ---
>  drivers/power/supply/twl4030_charger.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/twl4030_charger.c b/drivers/power/supply/twl4030_charger.c
> index b72838663872..c954b7234393 100644
> --- a/drivers/power/supply/twl4030_charger.c
> +++ b/drivers/power/supply/twl4030_charger.c
> @@ -421,7 +421,8 @@ static void twl4030_current_worker(struct work_struct *data)
>  
>  	if (v < USB_MIN_VOLT) {
>  		/* Back up and stop adjusting. */
> -		bci->usb_cur -= USB_CUR_STEP;
> +		if (bci->usb_cur >= USB_CUR_STEP)
> +			bci->usb_cur -= USB_CUR_STEP;
>  		bci->usb_cur_target = bci->usb_cur;
>  	} else if (bci->usb_cur >= bci->usb_cur_target ||
>  		   bci->usb_cur + USB_CUR_STEP > USB_MAX_CURRENT) {

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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