hwmon: (nct6775) Fix loop limit

[ Upstream commit 91bb8f45f73f19a0150c233c0f11cdeb6d71d1e9 ]

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>
Tested-by: Paul Menzel <pmenzel+linux-hwmon@molgen.mpg.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index aebce560bfaf39bbe826ab8cf3a1e2c5fb5895ca..b14eb73bc3c9bcdf3158bbe0b46605f60b5ab355 100644 (file)
--- 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])