linux-kernel - Re: [PATCH] signal: Fix the error return of kill -1

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Date:   Mon, 14 Aug 2023 16:06:52 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Petr Skocik <pskocik@...il.com>, Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Marco Elver <elver@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] signal: Fix the error return of kill -1

Hi Eric,

This change LGTM, but ...

On 08/11, Eric W. Biederman wrote:
>
> @@ -1602,7 +1603,8 @@ static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
>  		ret = __kill_pgrp_info(sig, info,
>  				pid ? find_vpid(-pid) : task_pgrp(current));
>  	} else {
> -		int retval = 0, count = 0;
> +		bool found = false, success = false;
> +		int retval = 0;
>  		struct task_struct * p;
>  
>  		for_each_process(p) {
> @@ -1610,12 +1612,12 @@ static int kill_something_info(int sig, struct kernel_siginfo *info, pid_t pid)
>  					!same_thread_group(p, current)) {
>  				int err = group_send_sig_info(sig, info, p,
>  							      PIDTYPE_MAX);
> -				++count;
> -				if (err != -EPERM)
> -					retval = err;
> +				found = true;
> +				success |= !err;
> +				retval = err;
>  			}
>  		}
> -		ret = count ? retval : -ESRCH;
> +		ret = success ? 0 : (found ? retval : -ESRCH);

Why do we need the "bool found" variable ? Afacis

	} else {
		bool success = false;
		int retval = -ESRCH;
		struct task_struct * p;

		for_each_process(p) {
			if (task_pid_vnr(p) > 1 &&
					!same_thread_group(p, current)) {
				int err = group_send_sig_info(sig, info, p,
							      PIDTYPE_MAX);
				success |= !err;
				retval = err;
			}
		}
		ret = success ? 0 : retval;
	}

does the same?

Oleg.