linux-kernel - Re: [PATCH] cpufreq: scpi: Prevent null pointer dereference in scpi_cpufreq_get

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Message-ID: <20250102050010.gnvf42r3v2ey7mww@vireshk-i7>
Date: Thu, 2 Jan 2025 10:30:10 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Charles Han <hanchunchao@...pur.com>
Cc: sudeep.holla@....com, cristian.marussi@....com, rafael@...nel.org,
	arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: scpi: Prevent null pointer dereference in
 scpi_cpufreq_get_rate()

On 30-12-24, 17:31, Charles Han wrote:
> cpufreq_cpu_get_raw() may return NULL if the cpu is not in
> policy->cpus cpu mask and it will cause null pointer dereference.
> Prevent null pointer dereference in scpi_cpufreq_get_rate().
> 
> Fixes: 343a8d17fa8d ("cpufreq: scpi: remove arm_big_little dependency")
> Signed-off-by: Charles Han <hanchunchao@...pur.com>
> ---
>  drivers/cpufreq/scpi-cpufreq.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
> index cd89c1b9832c..c888ed3a0de9 100644
> --- a/drivers/cpufreq/scpi-cpufreq.c
> +++ b/drivers/cpufreq/scpi-cpufreq.c
> @@ -30,6 +30,9 @@ static struct scpi_ops *scpi_ops;
>  static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
>  {
>  	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
> +	if (unlikely(!policy))
> +		return 0;
> +
>  	struct scpi_data *priv = policy->driver_data;
>  	unsigned long rate = clk_get_rate(priv->clk);

The check needs to be made after all the variable definitions.

-- 
viresh