tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

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 <psanman@juniper.net>
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 <linux@roeck-us.net>

authored by

Sanman Pradhan and committed by
Guenter Roeck 39e2a5bf ca34ee6d

+8 -9
+8 -9
drivers/hwmon/occ/common.c
··· 420 420 return sysfs_emit(buf, "%u\n", val); 421 421 } 422 422 423 + static u64 occ_get_powr_avg(u64 accum, u32 samples) 424 + { 425 + return (samples == 0) ? 0 : 426 + mul_u64_u32_div(accum, 1000000UL, samples); 427 + } 428 + 423 429 static ssize_t occ_show_power_1(struct device *dev, 424 430 struct device_attribute *attr, char *buf) 425 431 { ··· 447 441 val = get_unaligned_be16(&power->sensor_id); 448 442 break; 449 443 case 1: 450 - val = get_unaligned_be32(&power->accumulator) / 451 - get_unaligned_be32(&power->update_tag); 452 - val *= 1000000ULL; 444 + val = occ_get_powr_avg(get_unaligned_be32(&power->accumulator), 445 + get_unaligned_be32(&power->update_tag)); 453 446 break; 454 447 case 2: 455 448 val = (u64)get_unaligned_be32(&power->update_tag) * ··· 462 457 } 463 458 464 459 return sysfs_emit(buf, "%llu\n", val); 465 - } 466 - 467 - static u64 occ_get_powr_avg(u64 accum, u32 samples) 468 - { 469 - return (samples == 0) ? 0 : 470 - mul_u64_u32_div(accum, 1000000UL, samples); 471 460 } 472 461 473 462 static ssize_t occ_show_power_2(struct device *dev,