From: Sanman Pradhan Date: Thu, 26 Mar 2026 22:45:23 +0000 (+0000) Subject: hwmon: (occ) Fix division by zero in occ_show_power_1() X-Git-Tag: v7.0-rc7~14^2~2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=39e2a5bf970402a8530a319cf06122e216ba57b8;p=thirdparty%2Flinux.git hwmon: (occ) Fix division by zero in occ_show_power_1() In occ_show_power_1() case 1, the accumulator is divided by update_tag without checking for zero. If no samples have been collected yet (e.g. during early boot when the sensor block is included but hasn't been updated), update_tag is zero, causing a kernel divide-by-zero crash. The 2019 fix in commit 211186cae14d ("hwmon: (occ) Fix division by zero issue") only addressed occ_get_powr_avg() used by occ_show_power_2() and occ_show_power_a0(). This separate code path in occ_show_power_1() was missed. Fix this by reusing the existing occ_get_powr_avg() helper, which already handles the zero-sample case and uses mul_u64_u32_div() to multiply before dividing for better precision. Move the helper above occ_show_power_1() so it is visible at the call site. Fixes: c10e753d43eb ("hwmon (occ): Add sensor types and versions") Cc: stable@vger.kernel.org Signed-off-by: Sanman Pradhan Link: https://lore.kernel.org/r/20260326224510.294619-2-sanman.pradhan@hpe.com [groeck: Fix alignment problems reported by checkpatch] Signed-off-by: Guenter Roeck --- diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c index 89928d38831b6..ec7dbb94de0b7 100644 --- a/drivers/hwmon/occ/common.c +++ b/drivers/hwmon/occ/common.c @@ -420,6 +420,12 @@ static ssize_t occ_show_freq_2(struct device *dev, return sysfs_emit(buf, "%u\n", val); } +static u64 occ_get_powr_avg(u64 accum, u32 samples) +{ + return (samples == 0) ? 0 : + mul_u64_u32_div(accum, 1000000UL, samples); +} + static ssize_t occ_show_power_1(struct device *dev, struct device_attribute *attr, char *buf) { @@ -441,9 +447,8 @@ static ssize_t occ_show_power_1(struct device *dev, val = get_unaligned_be16(&power->sensor_id); break; case 1: - val = get_unaligned_be32(&power->accumulator) / - get_unaligned_be32(&power->update_tag); - val *= 1000000ULL; + val = occ_get_powr_avg(get_unaligned_be32(&power->accumulator), + get_unaligned_be32(&power->update_tag)); break; case 2: val = (u64)get_unaligned_be32(&power->update_tag) * @@ -459,12 +464,6 @@ static ssize_t occ_show_power_1(struct device *dev, return sysfs_emit(buf, "%llu\n", val); } -static u64 occ_get_powr_avg(u64 accum, u32 samples) -{ - return (samples == 0) ? 0 : - mul_u64_u32_div(accum, 1000000UL, samples); -} - static ssize_t occ_show_power_2(struct device *dev, struct device_attribute *attr, char *buf) {