linux-kernel - Re: [PATCH 1/1] Fix kill(-1,s) returning 0 on 0 kills

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Message-ID: <20221123103016.GA32207@redhat.com>
Date:   Wed, 23 Nov 2022 11:30:17 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Petr Skocik <pskocik@...il.com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.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 1/1] Fix kill(-1,s) returning 0 on 0 kills

On 11/22, Petr Skocik wrote:
>
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1600,20 +1600,18 @@ 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;
>  		struct task_struct * p;
>  
> +		ret = -ESRCH;
>  		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);
> -				++count;
>  				if (err != -EPERM)
> -					retval = err;
> +					ret = err; /*either all 0 or all -EINVAL*/

The patch looks good to me, and it also simplifies the code.

But I fail to understand the /*either all 0 or all -EINVAL*/ comment above..

Oleg.