linux-kernel - Re: [PATCH] cpufreq: CPPC: Fix possible null-ptr-deref for cppc_get_cpu

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Message-ID: <20241030090857.xbnpfnpi4hp4emkk@vireshk-i7>
Date: Wed, 30 Oct 2024 14:38:57 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: rafael@...nel.org, Pierre.Gondois@....com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: CPPC: Fix possible null-ptr-deref for
 cppc_get_cpu_cost()

On 30-10-24, 16:24, Jinjie Ruan 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,
> so check NULL for cppc_get_cpu_cost().
> 
> Fixes: 740fcdc2c20e ("cpufreq: CPPC: Register EM based on efficiency class information")
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  drivers/cpufreq/cppc_cpufreq.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index 2b8708475ac7..67fa97bbeae7 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -487,6 +487,9 @@ static int cppc_get_cpu_cost(struct device *cpu_dev, unsigned long KHz,
>  	int step;
>  
>  	policy = cpufreq_cpu_get_raw(cpu_dev->id);
> +	if (!policy)
> +		return 0;
> +
>  	cpu_data = policy->driver_data;
>  	perf_caps = &cpu_data->perf_caps;
>  	max_cap = arch_scale_cpu_capacity(cpu_dev->id);

Applied. Thanks.

-- 
viresh