1. Patchew
  2. linux
  3. View series

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

Kaushlendra Kumar posted 1 patch 1 week, 1 day ago
There is a newer version of this series
drivers/base/arch_topology.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Kaushlendra Kumar 1 week, 1 day ago 
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.

Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
---
 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
Re: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Sudeep Holla 1 week, 1 day ago 
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@arm.com>

> Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
> ---
>  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
Re: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Dan Carpenter 1 week, 1 day ago 
On Tue, Sep 23, 2025 at 09:40:28AM +0100, Sudeep Holla wrote:
> 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 don't think of_clk_get() can actually return NULL...  It's still worth
fixing but I don't think it affects real life.

regards,
dan carpenter
Re: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Sudeep Holla 1 week, 1 day ago 
On Tue, Sep 23, 2025 at 01:24:41PM +0300, Dan Carpenter wrote:
> On Tue, Sep 23, 2025 at 09:40:28AM +0100, Sudeep Holla wrote:
> > 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 don't think of_clk_get() can actually return NULL...  It's still worth
> fixing but I don't think it affects real life.
> 

Ah that explains, just looked at PTR_ERR_OR_ZERO and wondered. Thanks
for the details.

-- 
Regards,
Sudeep
Re: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Markus Elfring 1 week, 1 day ago 
…
> 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.

* Can the change description be refined based on documented macro call properties?
  https://elixir.bootlin.com/linux/v6.17-rc7/source/include/linux/err.h#L101-L123

* How do you think about to add any tags (like “Fixes” and “Cc”) accordingly?


Regards,
Markus
RE: [PATCH] arch_topology: Fix incorrect error check in topology_parse_cpu_capacity()
Posted by Kumar, Kaushlendra 1 week, 1 day ago 
On [Date], Markus Elfring <Markus.Elfring@web.de> wrote:
> > 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.
> 
> * Can the change description be refined based on documented macro call properties?
>   https://elixir.bootlin.com/linux/v6.17-rc7/source/include/linux/err.h#L101-L123
> 
> * How do you think about to add any tags (like "Fixes" and "Cc") accordingly?

Hi Markus,

Thank you for the valuable feedback and the documentation reference.

Created a v2 patch with the corrected description based on the documented 
behavior.

Best regards,
Kaushlendra

Patchew 2.1-devel-b67e4c2

© 2016 - 2025 Red Hat, Inc.