Re: [PATCH 1/3] hwmon: (occ) Fix division by zero in occ_show_power_1()

[Guenter Roeck]

On Thu, Mar 26, 2026 at 10:45:23PM +0000, Pradhan, Sanman wrote:
> From: Sanman Pradhan <psanman@xxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Sanman Pradhan <psanman@xxxxxxxxxxx>

Applied.

Thanks,
Guenter