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

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