Re: [PATCH bpf v3] bpf: fix NULL pointer dereference in bpf_task_from_vpid()

[Leon Hwang]

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);