[PATCH 3.2 140/185] hwmon: Prevent some divide by zeros inFAN_TO_REG()

From: Ben Hutchings
Date: Sat Dec 28 2013 - 21:44:42 EST


3.2.54-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

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@xxxxxxxxxx>
Acked-by: Roger Lucas <vt8231@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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
@@ -90,6 +90,8 @@ static inline u8 FAN_TO_REG(long rpm, in
{
if (rpm <= 0)
return 255;
+ if (rpm > 1350000)
+ return 1;
return SENSORS_LIMIT((1350000 + rpm * div / 2) / (rpm * div), 1, 254);
}

--- a/drivers/hwmon/sis5595.c
+++ b/drivers/hwmon/sis5595.c
@@ -133,6 +133,8 @@ static inline u8 FAN_TO_REG(long rpm, in
{
if (rpm <= 0)
return 255;
+ if (rpm > 1350000)
+ return 1;
return SENSORS_LIMIT((1350000 + rpm * div / 2) / (rpm * div), 1, 254);
}

--- a/drivers/hwmon/vt8231.c
+++ b/drivers/hwmon/vt8231.c
@@ -139,7 +139,7 @@ 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 SENSORS_LIMIT(1310720 / (rpm * div), 1, 255);
}

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