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From: Leon Hwang <leon.hwang@linux.dev>
To: Sechang Lim <rhkrqnwk98@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Eduard Zingerman <eddyz87@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	Jiri Olsa <jolsa@kernel.org>,
	Juntong Deng <juntong.deng@outlook.com>,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf v3] bpf: fix NULL pointer dereference in bpf_task_from_vpid()
Date: Sat, 6 Jun 2026 20:57:34 +0800	[thread overview]
Message-ID: <cf8cef69-85c6-4d6f-b3f3-eb79fb2e075d@linux.dev> (raw)
In-Reply-To: <20260606091941.1803115-1-rhkrqnwk98@gmail.com>

On 2026/6/6 17:19, Sechang Lim wrote:
[...]
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index b5314c9fed3c..226c31ccb5d6 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -2912,7 +2912,14 @@ __bpf_kfunc struct task_struct *bpf_task_from_vpid(s32 vpid)
>  {
>  	struct task_struct *p;
>  
> +	if (in_interrupt())
> +		return NULL;
> +
>  	rcu_read_lock();

Better to use guard(rcu)() here, and drop the rcu_read_unlock().

Thanks,
Leon

> +	if (!task_active_pid_ns(current)) {
> +		rcu_read_unlock();
> +		return NULL;
> +	}
>  	p = find_task_by_vpid(vpid);
>  	if (p)
>  		p = bpf_task_acquire(p);


  parent reply	other threads:[~2026-06-06 12:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-06  9:19 [PATCH bpf v3] bpf: fix NULL pointer dereference in bpf_task_from_vpid() Sechang Lim
2026-06-06  9:31 ` sashiko-bot
2026-06-06  9:58 ` bot+bpf-ci
2026-06-06 12:57 ` Leon Hwang [this message]
2026-06-07  8:44 ` Kumar Kartikeya Dwivedi
2026-06-07 10:05   ` Sechang Lim
2026-06-07 11:06     ` Kumar Kartikeya Dwivedi

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