From: Gui-Dong Han Date: Wed, 26 Nov 2025 11:40:46 +0000 (+0800) Subject: hwmon: (adm1029) Add locking to avoid TOCTOU X-Git-Tag: v6.19-rc1~148^2~8 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9eb4fb93069a889aae955c2fbf78f9eb34ac4562;p=thirdparty%2Fkernel%2Flinux.git hwmon: (adm1029) Add locking to avoid TOCTOU The function fan_show checks shared data for zero or invalid values before using it as a divisor. These accesses are currently lockless. If the data changes to zero between the check and the division, it causes a divide-by-zero error. Explicitly acquire the update lock around these checks and calculations to ensure the data remains stable, preventing Time-of-Check to Time-of-Use (TOCTOU) race conditions. Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/ Signed-off-by: Gui-Dong Han Link: https://lore.kernel.org/r/20251126114047.10039-1-hanguidong02@gmail.com Signed-off-by: Guenter Roeck --- diff --git a/drivers/hwmon/adm1029.c b/drivers/hwmon/adm1029.c index 761c130924884..71eea8ae51b95 100644 --- a/drivers/hwmon/adm1029.c +++ b/drivers/hwmon/adm1029.c @@ -171,14 +171,17 @@ fan_show(struct device *dev, struct device_attribute *devattr, char *buf) struct adm1029_data *data = adm1029_update_device(dev); u16 val; + mutex_lock(&data->update_lock); if (data->fan[attr->index] == 0 || (data->fan_div[attr->index] & 0xC0) == 0 || data->fan[attr->index] == 255) { + mutex_unlock(&data->update_lock); return sprintf(buf, "0\n"); } val = 1880 * 120 / DIV_FROM_REG(data->fan_div[attr->index]) / data->fan[attr->index]; + mutex_unlock(&data->update_lock); return sprintf(buf, "%d\n", val); }