[PATCH] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

[PATCH] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

[Wen Yang]

The cpu variable is still being used in the of_get_property() call
after the of_node_put() call, which may result in use-after-free.

Fixes: a9acc26b75f ("cpufreq/pasemi: fix possible object reference leak")
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/cpufreq/pasemi-cpufreq.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 6b1e4ab..d2dd47b 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -132,7 +132,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	cpu = of_get_cpu_node(policy->cpu, NULL);
 
-	of_node_put(cpu);
 	if (!cpu)
 		goto out;
 
@@ -141,15 +140,15 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		dn = of_find_compatible_node(NULL, NULL,
 					     "pasemi,pwrficient-sdc");
 	if (!dn)
-		goto out;
+		goto out_put_cpu_node;
 	err = of_address_to_resource(dn, 0, &res);
 	of_node_put(dn);
 	if (err)
-		goto out;
+		goto out_put_cpu_node;
 	sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
 	if (!sdcasr_mapbase) {
 		err = -EINVAL;
-		goto out;
+		goto out_put_cpu_node;
 	}
 
 	dn = of_find_compatible_node(NULL, NULL, "1682m-gizmo");
@@ -177,6 +176,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		err = -EINVAL;
 		goto out_unmap_sdcpwr;
 	}
+	of_node_put(cpu);
 
 	/* we need the freq in kHz */
 	max_freq = *max_freqp / 1000;
@@ -203,6 +203,8 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 out_unmap_sdcasr:
 	iounmap(sdcasr_mapbase);
+out_put_cpu_node:
+	of_node_put(cpu);
 out:
 	return err;
 }
-- 
2.9.5

Re: [PATCH] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

[Viresh Kumar]

On 08-07-19, 14:19, Wen Yang wrote:
> The cpu variable is still being used in the of_get_property() call
> after the of_node_put() call, which may result in use-after-free.
> 
> Fixes: a9acc26b75f ("cpufreq/pasemi: fix possible object reference leak")
> Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-pm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/cpufreq/pasemi-cpufreq.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

I will suggest some changes here.

> diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
> index 6b1e4ab..d2dd47b 100644
> --- a/drivers/cpufreq/pasemi-cpufreq.c
> +++ b/drivers/cpufreq/pasemi-cpufreq.c
> @@ -132,7 +132,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)

Don't initialize "err" anymore.

>  	cpu = of_get_cpu_node(policy->cpu, NULL);
>  
> -	of_node_put(cpu);
>  	if (!cpu)
>  		goto out;

Do return -ENODEV; here.

>  
> @@ -141,15 +140,15 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
>  		dn = of_find_compatible_node(NULL, NULL,
>  					     "pasemi,pwrficient-sdc");
>  	if (!dn)
> -		goto out;
> +		goto out_put_cpu_node;
>  	err = of_address_to_resource(dn, 0, &res);
>  	of_node_put(dn);
>  	if (err)
> -		goto out;
> +		goto out_put_cpu_node;
>  	sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
>  	if (!sdcasr_mapbase) {
>  		err = -EINVAL;
> -		goto out;
> +		goto out_put_cpu_node;
>  	}

Don't do above changes.

>  
>  	dn = of_find_compatible_node(NULL, NULL, "1682m-gizmo");
> @@ -177,6 +176,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
>  		err = -EINVAL;
>  		goto out_unmap_sdcpwr;
>  	}
> +	of_node_put(cpu);
>  
>  	/* we need the freq in kHz */
>  	max_freq = *max_freqp / 1000;
> @@ -203,6 +203,8 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
>  
>  out_unmap_sdcasr:
>  	iounmap(sdcasr_mapbase);
> +out_put_cpu_node:

Don't add this label, instead use "out" for also having the below
code.

> +	of_node_put(cpu);
>  out:
>  	return err;
>  }
> -- 
> 2.9.5

-- 
viresh