[PATCH v2 5/5] iio: humidity: hts221: fix division by zero in calibration parsing
Adi Nata <[email protected]>
| Newsgroups | dev.linux.lists.linux-kernel-mentees,org.kernel.vger.linux-iio,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
hts221_parse_rh_caldata() and hts221_parse_temp_caldata() divide by (cal_x1 - cal_x0) without checking that the two calibration points differ can cause division by zero. Reject zero divisor with -EINVAL, logging the offending calibration values. A device with such calibration data cannot produce meaningful scale or offset values anyway. Signed-off-by: Adi Nata <[email protected]> --- drivers/iio/humidity/hts221_core.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/iio/humidity/hts221_core.c b/drivers/iio/humidity/hts221_core.c index fda38dfc6742..47a10884d812 100644 --- a/drivers/iio/humidity/hts221_core.c +++ b/drivers/iio/humidity/hts221_core.c @@ -245,6 +245,7 @@ int hts221_set_enable(struct hts221_hw *hw, bool enable) static int hts221_parse_temp_caldata(struct hts221_hw *hw) { + struct device *dev = hw->dev; int err, *slope, *b_gen, cal0, cal1; s16 cal_x0, cal_x1, cal_y0, cal_y1; __le16 val; @@ -275,10 +276,20 @@ static int hts221_parse_temp_caldata(struct hts221_hw *hw) return err; cal_x1 = le16_to_cpu(val); + if (cal_x1 == cal_x0) + return dev_err_probe(dev, -EINVAL, + "invalid temperature calibration points (x0 %d, x1 %d)\n", + cal_x0, cal_x1); + slope = &hw->sensors[HTS221_SENSOR_T].slope; b_gen = &hw->sensors[HTS221_SENSOR_T].b_gen; *slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0); + if (!*slope) + return dev_err_probe(dev, -EINVAL, + "invalid temperature calibration slope (y0 %d, y1 %d)\n", + cal_y0, cal_y1); + *b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) / (cal_x1 - cal_x0); *b_gen *= 8; @@ -288,6 +299,7 @@ static int hts221_parse_temp_caldata(struct hts221_hw *hw) static int hts221_parse_rh_caldata(struct hts221_hw *hw) { + struct device *dev = hw->dev; int err, *slope, *b_gen, data; s16 cal_x0, cal_x1, cal_y0, cal_y1; __le16 val; @@ -314,10 +326,20 @@ static int hts221_parse_rh_caldata(struct hts221_hw *hw) return err; cal_x1 = le16_to_cpu(val); + if (cal_x1 == cal_x0) + return dev_err_probe(dev, -EINVAL, + "invalid rh calibration points (x0 %d, x1 %d)\n", + cal_x0, cal_x1); + slope = &hw->sensors[HTS221_SENSOR_H].slope; b_gen = &hw->sensors[HTS221_SENSOR_H].b_gen; *slope = ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0); + if (!*slope) + return dev_err_probe(dev, -EINVAL, + "invalid rh calibration slope (y0 %d, y1 %d)\n", + cal_y0, cal_y1); + *b_gen = (((s32)cal_x1 * cal_y0 - (s32)cal_x0 * cal_y1) * 1000) / (cal_x1 - cal_x0); *b_gen *= 8; -- 2.47.3