linux-kernel - [PATCH] IIO: bmp280-core.c: fix error in humidity calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 27 Mar 2017 12:06:47 +0200
From:   Andreas Klinger <ak@...klinger.de>
To:     jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net, linus.walleij@...aro.org, ddvlad@...il.com,
        akinobu.mita@...il.com, yongjun_wei@...ndmicro.com.cn,
        a.mathur@...sung.com
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] IIO: bmp280-core.c: fix error in humidity calculation

While calculating the compensation of the humidity there are negative
values interpreted as unsigned because of unsigned variables used.
These values need to be casted to signed as indicated by the documentation
of the sensor.

Signed-off-by: Andreas Klinger <ak@...klinger.de>
---
 drivers/iio/pressure/bmp280-core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 4d18826ac63c..73308f0ea260 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -177,9 +177,9 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data,
 
 	var = ((s32)data->t_fine) - 76800;
 	var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
-		* (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
-		+ 2097152) * H2 + 8192) >> 14);
-	var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;
+		* (((((((var * H6) >> 10) * (((var * (s32)H3) >> 11) + 32768))
+		>> 10) + 2097152) * H2 + 8192) >> 14);
+	var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4;
 
 	return var >> 12;
 };
-- 
2.1.4


--