[PATCH] hwmon: (nct6775) Fix loop limit

Guenter Roeck
2018-06-13T15:10:40Z

Commit cc66b3038254 ("hwmon: (nct6775) Rework temperature source and label
handling") changed a loop limit from "data->temp_label_num - 1" to "32",
as part of moving from a string array to a bit mask. This results in the
following error, reported by UBSAN.

UBSAN: Undefined behaviour in drivers/hwmon/nct6775.c:4179:27
shift exponent 32 is too large for 32-bit type 'long unsigned int'

Similar to the original loop, the limit has to be one less than the
number of bits.

Fixes: cc66b3038254 ("hwmon: (nct6775) Rework temperature source and label handling")
Reported-by: Paul Menzel <pmenzel+linux-hwmon@molgen.mpg.de>
Cc: Paul Menzel <pmenzel+linux-hwmon@molgen.mpg.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
drivers/hwmon/nct6775.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index aebce560bfaf..b14eb73bc3c9 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -4175,7 +4175,7 @@ static int nct6775_probe(struct platform_device *pdev)
* The temperature is already monitored if the respective bit in <mask>
* is set.
*/
- for (i = 0; i < 32; i++) {
+ for (i = 0; i < 31; i++) {
if (!(data->temp_mask & BIT(i + 1)))
continue;
if (!reg_temp_alternate[i])
--
2.7.4