2022-12-30 08:17:03

by Miaoqian Lin

Subject: [PATCH] powercap/dtpm_cpu: Fix refcount leak in __dtpm_cpu_setup

The policy return by cpufreq_cpu_get() should be released with
cpufreq_cpu_put() to balance the reference counter.
Add missing cpufreq_cpu_put() to fix this.

Fixes: 0e8f68d7f048 ("powercap/drivers/dtpm: Add CPU energy model based support")
Signed-off-by: Miaoqian Lin <[email protected]>
---
drivers/powercap/dtpm_cpu.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index 2ff7717530bf..3083c6b45c90 100644
--- a/drivers/powercap/dtpm_cpu.c
+++ b/drivers/powercap/dtpm_cpu.c
@@ -195,12 +195,16 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
return 0;

pd = em_cpu_get(cpu);
- if (!pd || em_is_artificial(pd))
- return -EINVAL;
+ if (!pd || em_is_artificial(pd)) {
+ ret = -EINVAL;
+ goto out_put_policy;
+ }

dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
- if (!dtpm_cpu)
- return -ENOMEM;
+ if (!dtpm_cpu) {
+ ret = -ENOMEM;
+ goto out_put_policy;
+ }

dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
dtpm_cpu->cpu = cpu;
@@ -220,6 +224,8 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
if (ret)
goto out_dtpm_unregister;

+ cpufreq_cpu_put(policy);
+
return 0;

out_dtpm_unregister:
@@ -230,7 +236,8 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
for_each_cpu(cpu, policy->related_cpus)
per_cpu(dtpm_per_cpu, cpu) = NULL;
kfree(dtpm_cpu);
-
+out_put_policy:
+ cpufreq_cpu_put(policy);
return ret;
}

--
2.25.1

2023-01-20 14:22:50

by Rafael J. Wysocki

Subject: Re: [PATCH] powercap/dtpm_cpu: Fix refcount leak in __dtpm_cpu_setup

On Fri, Dec 30, 2022 at 8:52 AM Miaoqian Lin <[email protected]> wrote:
>
> The policy return by cpufreq_cpu_get() should be released with
> cpufreq_cpu_put() to balance the reference counter.
> Add missing cpufreq_cpu_put() to fix this.
>
> Fixes: 0e8f68d7f048 ("powercap/drivers/dtpm: Add CPU energy model based support")
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> drivers/powercap/dtpm_cpu.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> index 2ff7717530bf..3083c6b45c90 100644
> --- a/drivers/powercap/dtpm_cpu.c
> +++ b/drivers/powercap/dtpm_cpu.c
> @@ -195,12 +195,16 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> return 0;
>
> pd = em_cpu_get(cpu);
> - if (!pd || em_is_artificial(pd))
> - return -EINVAL;
> + if (!pd || em_is_artificial(pd)) {
> + ret = -EINVAL;
> + goto out_put_policy;
> + }
>
> dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
> - if (!dtpm_cpu)
> - return -ENOMEM;
> + if (!dtpm_cpu) {
> + ret = -ENOMEM;
> + goto out_put_policy;
> + }
>
> dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
> dtpm_cpu->cpu = cpu;
> @@ -220,6 +224,8 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> if (ret)
> goto out_dtpm_unregister;

The part of the patch above is valid, but I don't think that the
policy reference counter can be dropped below, because that may allow
the policy to go away and this driver will be still using it, won't
it?

>
> + cpufreq_cpu_put(policy);
> +
> return 0;
>
> out_dtpm_unregister:
> @@ -230,7 +236,8 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> for_each_cpu(cpu, policy->related_cpus)
> per_cpu(dtpm_per_cpu, cpu) = NULL;
> kfree(dtpm_cpu);
> -
> +out_put_policy:
> + cpufreq_cpu_put(policy);
> return ret;
> }
>
> --
> 2.25.1
>