Re: [PATCH] hwmon: (coretemp) Fix core_data leak on CPUs without PTS

[Guenter Roeck]

On Mon, Aug 10, 2026 at 09:23:44PM +0200, Szymon Wilczek wrote:
> pdata->core_data is allocated in init_temp_data() when the first core
> temp_data of a package is created, but it is only released from
> destroy_temp_data(), and only in the branch that handles the package
> temp_data.
> 
> Package temp_data is created solely when the CPU supports
> X86_FEATURE_PTS. On a CPU without it, coretemp_cpu_online() never calls
> coretemp_add_core() with pkg_flag set, so pdata->pkg_data stays NULL.
> coretemp_cpu_offline() then skips the removal of the package interface,
> destroy_temp_data() is never called for package data, and the array is
> still allocated when coretemp_device_remove() frees the platform data
> that pointed at it.
> 
> Release the array in coretemp_device_remove(). destroy_temp_data() sets
> pdata->core_data to NULL when it frees it, so the added kfree() is a
> no-op on CPUs that do have PTS.
> 
> Tested on an Intel Core i5-1135G7. The driver was instrumented to log
> every allocation and release of pdata->core_data, and the PTS check in
> coretemp_cpu_online() was patched out to emulate a CPU without package
> thermal support. Without this change the array was allocated and never
> released, and coretemp_device_remove() still saw a non-NULL pointer.
> With it the array is released and the pointer accounting balances. On an
> unmodified build the release still happens via the package temp_data and
> the added kfree() sees NULL, with no slab warnings over repeated module
> load and unload cycles.
> 
> Fixes: 1a793caf6f69 ("hwmon: (coretemp) Use dynamic allocated memory for core temp_data")
> Signed-off-by: Szymon Wilczek <swilczek.lx@xxxxxxxxx>

Applied.

Thanks,
Guenter