linux-kernel - Re: [PATCH 2/2] ptrace: Return the signal to continue with from ptrace

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Message-ID: <20220317180856.GB13318@redhat.com>
Date:   Thu, 17 Mar 2022 19:08:57 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexey Gladkov <legion@...nel.org>,
        Kyle Huey <me@...ehuey.com>, Kees Cook <keescook@...omium.org>,
        Al Viro <viro@...IV.linux.org.uk>, linux-api@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH 2/2] ptrace: Return the signal to continue with from
 ptrace_stop

Not sure I understand this patch, I can't apply it. I guess I need to
clone your tree first, will do later.

Just one question right now,

On 03/15, Eric W. Biederman wrote:
>
> +static int ptrace_stop(int exit_code, int why, int clear_code,
>  			unsigned long message, kernel_siginfo_t *info)
>  	__releases(&current->sighand->siglock)
>  	__acquires(&current->sighand->siglock)
>  {
>  	bool gstop_done = false;
> +	bool read_code = true;
>  
>  	if (arch_ptrace_stop_needed()) {
>  		/*
> @@ -2305,8 +2307,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code,
>  
>  		/* tasklist protects us from ptrace_freeze_traced() */
>  		__set_current_state(TASK_RUNNING);
> +		read_code = false;
>  		if (clear_code)
> -			current->exit_code = 0;
> +			exit_code = 0;
>  		read_unlock(&tasklist_lock);
>  	}
>  
> @@ -2316,8 +2319,10 @@ static void ptrace_stop(int exit_code, int why, int clear_code,
>  	 * any signal-sending on another CPU that wants to examine it.
>  	 */
>  	spin_lock_irq(&current->sighand->siglock);
> +	if (read_code) exit_code = current->exit_code;

style ;)

>  	current->last_siginfo = NULL;
>  	current->ptrace_message = 0;
> +	current->exit_code = 0;

OK, I like it... but can't we remove the ugly "int clear_code" arg?

Oleg.