Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 23 Nov 2022 12:56:38 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Petr Skocik <pskocik@gmail.com>
Cc:     "Eric W. Biederman" <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Marco Elver <elver@google.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] Fix kill(-1,s) returning 0 on 0 kills
Message-ID: <20221123115637.GD32207@redhat.com>
References: <20221122161240.137570-1-pskocik@gmail.com>
 <20221122161240.137570-2-pskocik@gmail.com>
 <20221123103016.GA32207@redhat.com>
 <dcfcb10b-10c9-eb37-b345-07735453f5b5@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <dcfcb10b-10c9-eb37-b345-07735453f5b5@gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Precedence: bulk

On 11/23, Petr Skocik wrote:
>
> On 11/23/22 11:30, Oleg Nesterov wrote:
> >
> >But I fail to understand the /*either all 0 or all -EINVAL*/ comment above..
> >
> >Oleg.
> >
> 
> Thanks. The comment is explained in my reply to Kees Cook:
> https://lkml.org/lkml/2022/11/22/1327.
> I felt like making it because without it to me it suspiciously looks like
> the
> `if ( err != -EPERM) ret = err;` (or `if ( err != -EPERM) retval = err;` in
> the original) could be masking
> a non-EPERM failure with a later success, but it isn't because in this
> context, all the non-EPERM return vals should either ALL be 0 or ALL be
> -EINVAL.

Ah, now I see what did you mean, thanks.

Well, you are probably right, __send_signal_locked() won't fail even if
__sigqueue_alloc() fails, because si_code = SI_USER.

Not sure we should rely on this, but I won't argue.

Oleg.