linux-kernel - Re: [PATCH] signal: trace_signal_deliver when signal_group

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Message-ID: <20190420112219.GB17468@redhat.com>
Date:   Sat, 20 Apr 2019 13:22:20 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Zhenliang Wei <weizhenliang@...wei.com>
Cc:     ebiederm@...ssion.com, colona@...sta.com,
        akpm@...ux-foundation.org, christian@...uner.io, arnd@...db.de,
        tglx@...utronix.de, deepa.kernel@...il.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] signal: trace_signal_deliver when signal_group_exit

On 04/20, Zhenliang Wei wrote:
>
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2441,6 +2441,8 @@ bool get_signal(struct ksignal *ksig)
>  	if (signal_group_exit(signal)) {
>  		ksig->info.si_signo = signr = SIGKILL;
>  		sigdelset(&current->pending.signal, SIGKILL);
> +		trace_signal_deliver(signr, &ksig->info,
> +				&sighand->action[signr - 1]);

Well, in this case ksig->info is not fully initialized for TP_STORE_SIGINFO()
which reads si_errno/si_code...

How about

		trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, SIG_DFL)

?

We know that action[SIGKILL] must be SIG_DFL.

And SEND_SIG_NOINFO matches the fact that SIGKILL doesn't have any info,
collect_signal() sets SI_USER and clears si_errno in this case.

Oleg.