Re: [PATCH 2/2] platform/x86/intel: power-domains: Handle failed init in tpmi_get_power_domain_mask()

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

On Thu, 2026-09-24 at 12:36 -0700, Kristen Carlson Accardi wrote:
> tpmi_init() returns early on CPU models that are not in tpmi_cpu_ids,
> before tpmi_power_domain_mask is allocated. When the driver is built
> in, the exported tpmi_get_power_domain_mask() remains callable after
> the failed init. It returns NULL then only because it indexes the
> NULL
> array at offset 0 for the zeroed per-CPU data. If cpuhp_setup_state()
> fails, the error path frees the array but leaves the pointer set, so
> the helper would return a pointer into freed memory.
> 
> Nothing in the tree calls tpmi_get_power_domain_mask() today, so this
> is hardening rather than a fix for a reachable bug. Return NULL when
> the array was not allocated, and clear the pointer wherever it is
> freed, as the previous patch does for domain_die_map.
> 
> Assisted-by: LLM
> Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>

    Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

> ---
>  drivers/platform/x86/intel/tpmi_power_domains.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/tpmi_power_domains.c
> b/drivers/platform/x86/intel/tpmi_power_domains.c
> index ea51fc56297d..d89b9894c42a 100644
> --- a/drivers/platform/x86/intel/tpmi_power_domains.c
> +++ b/drivers/platform/x86/intel/tpmi_power_domains.c
> @@ -139,6 +139,13 @@ cpumask_t *tpmi_get_power_domain_mask(int
> cpu_no)
>  	cpumask_t *mask;
>  	int index;
>  
> +	/*
> +	 * When built in, this stays callable after tpmi_init()
> failed
> +	 * before allocating the array.
> +	 */
> +	if (!tpmi_power_domain_mask)
> +		return NULL;
> +
>  	if (cpu_no >= num_possible_cpus())
>  		return NULL;
>  
> @@ -256,6 +263,7 @@ static int __init tpmi_init(void)
>  
>  free_domain_mask:
>  	kfree(tpmi_power_domain_mask);
> +	tpmi_power_domain_mask = NULL;
>  
>  	return ret;
>  }
> @@ -265,6 +273,7 @@ static void __exit tpmi_exit(void)
>  {
>  	cpuhp_remove_state(tpmi_hp_state);
>  	kfree(tpmi_power_domain_mask);
> +	tpmi_power_domain_mask = NULL;
>  	kfree(domain_die_map);
>  	domain_die_map = NULL;
>  }