From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Mon, 12 Dec 2016 11:03:55 +0100 From: Jean Delvare To: Guenter Roeck Cc: Hardware Monitoring Subject: Re: [PATCH v2] hwmon: (nct7802) Fix overflows seen when writing into limit attributes Message-ID: <20161212110355.7907737e@endymion> In-Reply-To: <1481316062-4999-1-git-send-email-linux@roeck-us.net> References: <1481316062-4999-1-git-send-email-linux@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-ID: On Fri, 9 Dec 2016 12:41:02 -0800, Guenter Roeck wrote: > Fix overflows seen when writing voltage and temperature limit attributes. > > The value passed to DIV_ROUND_CLOSEST() needs to be clamped, and the > value parameter passed to nct7802_write_fan_min() is an unsigned long. > > Also, writing values larger than 2700000 into a limit attribute results > in writing 0 into the chip's limit registers. You are only talking about _fan_ limits, right? > The exact behavior when > writing this value is unspecified. For consistency, report a limit of > 1350000 if the chip register reads 0. This may be wrong, and the chip > behavior should be verified with the actual chip, but it is better than > reporting a value of 0 (which, if written, results in writing a value > of 0x1fff into the chip register). This fix is good by doesn't seem to be related with the overflows? > > Fixes: 3434f3783580 ("hwmon: Driver for Nuvoton NCT7802Y") > Signed-off-by: Guenter Roeck > --- > v2: When reading a register value of 0 from a limit register, > report it as speed of 1350000. > Avoid overflow due to different variable types passed to > nct7802_write_fan_min(). > Fix low limit in store_temp (-128, not -127 as in v1). > > drivers/hwmon/nct7802.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/hwmon/nct7802.c b/drivers/hwmon/nct7802.c > index 3ce33d244cc0..12b94b094c0d 100644 > --- a/drivers/hwmon/nct7802.c > +++ b/drivers/hwmon/nct7802.c > @@ -259,13 +259,15 @@ static int nct7802_read_fan_min(struct nct7802_data *data, u8 reg_fan_low, > ret = 0; > else if (ret) > ret = DIV_ROUND_CLOSEST(1350000U, ret); > + else > + ret = 1350000U; > abort: > mutex_unlock(&data->access_lock); > return ret; > } > > static int nct7802_write_fan_min(struct nct7802_data *data, u8 reg_fan_low, > - u8 reg_fan_high, unsigned int limit) > + u8 reg_fan_high, unsigned long limit) > { > int err; > > @@ -326,8 +328,8 @@ static int nct7802_write_voltage(struct nct7802_data *data, int nr, int index, > int shift = 8 - REG_VOLTAGE_LIMIT_MSB_SHIFT[index - 1][nr]; > int err; > > + voltage = clamp_val(voltage, 0, 0x3ff * nct7802_vmul[nr]); > voltage = DIV_ROUND_CLOSEST(voltage, nct7802_vmul[nr]); > - voltage = clamp_val(voltage, 0, 0x3ff); > > mutex_lock(&data->access_lock); > err = regmap_write(data->regmap, > @@ -402,7 +404,7 @@ static ssize_t store_temp(struct device *dev, struct device_attribute *attr, > if (err < 0) > return err; > > - val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -128, 127); > + val = DIV_ROUND_CLOSEST(clamp_val(val, -128000, 127000), 1000); > > err = regmap_write(data->regmap, nr, val & 0xff); > return err ? : count; Reviewed-by: Jean Delvare -- Jean Delvare SUSE L3 Support