Re: [PATCH 1/3] hwmon: (coretemp) Check for NULL platform device in hotplug callbacks

[sashiko-bot@kernel.org]

> coretemp_get_pdev() returns NULL when topology_logical_die_id(cpu) is
> negative (such as -ENODEV or -ERANGE from topology_get_logical_id() on a
> firmware/hardware APIC ID mismatch) or exceeds max_zones (for example,
> under asymmetric or anomalous ACPI die topologies where
> topology_max_packages() * topology_max_dies_per_package() is smaller
> than the logical die count).
> 
> Commit 6d03bbff456b ("hwmon: (coretemp) Simplify platform device
> handling") pre-allocated zone_devices[0 .. max_zones - 1] during module
> init and dropped the NULL checks on pdev in coretemp_cpu_online() and
> coretemp_cpu_offline(), passing pdev unconditionally to
> platform_get_drvdata(). When coretemp_get_pdev() returns NULL,
> platform_get_drvdata(pdev) dereferences &pdev->dev and triggers a kernel
> NULL pointer dereference.
> 
> Check for a NULL pdev and return 0 in both coretemp_cpu_online() and
> coretemp_cpu_offline() before calling platform_get_drvdata(). Returning
> 0 in coretemp_cpu_online() ignores the unmapped CPU without blocking CPU
> bringup or tearing down valid thermal zones on other dies.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Fixes: 6d03bbff456b ("hwmon: (coretemp) Simplify platform device handling")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261031153528.3195123-1-linux@roeck-us.net?part=1