Re: [PATCH 1/3] hwmon: (acpi_power_meter) Fix missing locking in sysfs show callbacks and resume

[sashiko-bot@kernel.org]

> During system resume, acpi_power_meter_resume() calls free_capabilities()
> and read_capabilities() without acquiring resource->lock. Because ACPI
> notifications run on the non-freezable kacpi_notify_wq workqueue, a
> concurrent METER_NOTIFY_CONFIG notification during resume can race with
> acpi_power_meter_resume() and trigger a double-free or use-after-free on
> the model_number, serial_number, and oem_info strings as well as
> concurrently overwrite resource->caps. When CONFIG_SUSPEND_FREEZER is
> disabled, concurrent sysfs readers can also dereference the freed
> capability strings mid-update.
> 
> In addition, none of the extra sysfs attribute show callbacks acquire
> res->lock:
> - power1_average_min_show() and power1_average_max_show() read the 64-bit
>   res->trip[] entries twice without locking while set_trip() modifies
>   them under res->lock (including temporarily storing a candidate value
> [ ... ]
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Fixes: de584afa5e18 ("hwmon driver for ACPI 4.0 power meters")
> Fixes: 16746ce8adfe ("hwmon: (acpi_power_meter) Replace the deprecated hwmon_device_register")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Sashiko has reviewed this patch and found no issues.

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