[PATCH 3.12 020/118] hwmon: Prevent some divide by zeros in FAN_TO_REG()

Greg Kroah-Hartman
2013-12-18T21:47:34Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit 3806b45ba4655147a011df03242cc197ab986c43 upstream.

The "rpm * div" operations can overflow here, so this patch adds an
upper limit to rpm to prevent that. Jean Delvare helped me with this
patch.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Roger Lucas <vt8231@hiddenengine.co.uk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hwmon/lm78.c | 2 ++
drivers/hwmon/sis5595.c | 2 ++
drivers/hwmon/vt8231.c | 2 +-
3 files changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/hwmon/lm78.c
+++ b/drivers/hwmon/lm78.c
@@ -94,6 +94,8 @@ static inline u8 FAN_TO_REG(long rpm, in
{
if (rpm <= 0)
return 255;
+ if (rpm > 1350000)
+ return 1;
return clamp_val((1350000 + rpm * div / 2) / (rpm * div), 1, 254);
}

--- a/drivers/hwmon/sis5595.c
+++ b/drivers/hwmon/sis5595.c
@@ -141,6 +141,8 @@ static inline u8 FAN_TO_REG(long rpm, in
{
if (rpm <= 0)
return 255;
+ if (rpm > 1350000)
+ return 1;
return clamp_val((1350000 + rpm * div / 2) / (rpm * div), 1, 254);
}

--- a/drivers/hwmon/vt8231.c
+++ b/drivers/hwmon/vt8231.c
@@ -145,7 +145,7 @@ static const u8 regtempmin[] = { 0x3a, 0
*/
static inline u8 FAN_TO_REG(long rpm, int div)
{
- if (rpm == 0)
+ if (rpm <= 0 || rpm > 1310720)
return 0;
return clamp_val(1310720 / (rpm * div), 1, 255);
}