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Date: Fri, 15 May 2026 06:27:05 -1000
From: Tejun Heo <tj@kernel.org>
To: Qing Ming <a0yami@mailbox.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
	cgroups@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cgroup/rstat: validate cpu before css_rstat_cpu() access
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References: <20260515122952.59209-1-a0yami@mailbox.org>
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In-Reply-To: <20260515122952.59209-1-a0yami@mailbox.org>

On Fri, May 15, 2026 at 08:29:52PM +0800, Qing Ming wrote:
> @@ -90,6 +91,9 @@ __bpf_kfunc void css_rstat_updated(struct cgroup_subsys_state *css, int cpu)
>  	     !IS_ENABLED(CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS)) && in_nmi())
>  		return;
>  
> +	if (unlikely(cpu < 0 || cpu >= nr_cpu_ids || !cpu_possible(cpu)))
> +		return;
> +

Can you please add this validation to the BPF kfunc that's exposing it?

Thanks.

-- 
tejun