Re: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()

[Sudeep Holla]

On Tue, Sep 23, 2025 at 12:55:20PM +0530, Kaushlendra Kumar wrote:
> Fix incorrect use of PTR_ERR_OR_ZERO() in topology_parse_cpu_capacity()
> which causes the code to proceed with NULL clock pointers. The current
> logic uses !PTR_ERR_OR_ZERO(cpu_clk) which evaluates to true for both
> valid pointers and NULL, leading to potential NULL pointer dereference
> in clk_get_rate().
> 
> PTR_ERR_OR_ZERO(cpu_clk) returns:
> - 0 if cpu_clk is a valid pointer or NULL
> - error code if cpu_clk is an error pointer
> 
> Therefore !PTR_ERR_OR_ZERO(cpu_clk) is true for both valid pointers and
> NULL, causing the code to call clk_get_rate(NULL) when of_clk_get()
> returns NULL. Replace with IS_ERR_OR_NULL() which correctly identifies
> only valid pointers, ensuring clk_get_rate() is called only with valid
> clock objects.
>

Nice catch, wonder how it survived so long unnoticed. I also checked
if PTR_ERR_OR_ZERO() is used in similar way anywhere else. This happens
to be the only occurrence.

I think it needs,

Fixes: b8fe128dad8f ("arch_topology: Adjust initial CPU capacities with current freq")

With that,

Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>

> Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@xxxxxxxxx>
> ---
>  drivers/base/arch_topology.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 1037169abb45..e1eff05bea4a 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -292,7 +292,7 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
>  		 * frequency (by keeping the initial capacity_freq_ref value).
>  		 */
>  		cpu_clk = of_clk_get(cpu_node, 0);
> -		if (!PTR_ERR_OR_ZERO(cpu_clk)) {
> +		if (!IS_ERR_OR_NULL(cpu_clk)) {
>  			per_cpu(capacity_freq_ref, cpu) =
>  				clk_get_rate(cpu_clk) / HZ_PER_KHZ;
>  			clk_put(cpu_clk);
> -- 
> 2.34.1
> 

-- 
Regards,
Sudeep