From ccd32e735de7a941906e093f8dca924bb05c5794 Mon Sep 17 00:00:00 2001 From: Vivien Didelot Date: Mon, 21 Mar 2011 17:59:35 +0100 Subject: hwmon: (sht15) Fix integer overflow in humidity calculation An integer overflow occurs in the calculation of RHlinear when the relative humidity is greater than around 30%. The consequence is a subtle (but noticeable) error in the resulting humidity measurement. Signed-off-by: Vivien Didelot Signed-off-by: Jean Delvare Cc: stable@kernel.org Cc: Jonathan Cameron --- drivers/hwmon/sht15.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c index 3ba7dd8..1a9c32d 100644 --- a/drivers/hwmon/sht15.c +++ b/drivers/hwmon/sht15.c @@ -333,11 +333,11 @@ static inline int sht15_calc_humid(struct sht15_data *data) const int c1 = -4; const int c2 = 40500; /* x 10 ^ -6 */ - const int c3 = -2800; /* x10 ^ -9 */ + const int c3 = -28; /* x 10 ^ -7 */ RHlinear = c1*1000 + c2 * data->val_humid/1000 - + (data->val_humid * data->val_humid * c3)/1000000; + + (data->val_humid * data->val_humid * c3) / 10000; return (temp - 25000) * (10000 + 80 * data->val_humid) / 1000000 + RHlinear; } -- cgit v1.1