linux-kernel - Re: [PATCHv2 bpf-next 1/4] bpf: Fix uprobe multi pid filter check

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Message-ID: <20240905140708.GA8336@redhat.com>
Date: Thu, 5 Sep 2024 16:07:08 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Tianyi Liu <i.pear@...look.com>,
	Masami Hiramatsu <mhiramat@...nel.org>, bpf@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCHv2 bpf-next 1/4] bpf: Fix uprobe multi pid filter check

On 09/05, Jiri Olsa wrote:
>
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -3207,7 +3207,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
>  	struct bpf_run_ctx *old_run_ctx;
>  	int err = 0;
>
> -	if (link->task && current->mm != link->task->mm)
> +	if (link->task && !same_thread_group(current, link->task))
>  		return 0;

plus the current check can return false negative if link->task->mm == NULL

Acked-by: Oleg Nesterov <oleg@...hat.com>