linux-kernel - Re: [PATCH v5] signal: trace_signal_deliver when signal_group

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Date:   Thu, 25 Apr 2019 15:14:28 +0200
From:   Christian Brauner <christian@...uner.io>
To:     Zhenliang Wei <weizhenliang@...wei.com>
Cc:     ebiederm@...ssion.com, oleg@...hat.com, colona@...sta.com,
        akpm@...ux-foundation.org, 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 v5] signal: trace_signal_deliver when signal_group_exit

On Thu, Apr 25, 2019 at 10:58:12AM +0800, Zhenliang Wei wrote:
> In the fixes commit, removing SIGKILL from each thread signal mask
> and executing "goto fatal" directly will skip the call to
> "trace_signal_deliver". At this point, the delivery tracking of the SIGKILL
> signal will be inaccurate.
> 
> Therefore, we need to add trace_signal_deliver before "goto fatal"
> after executing sigdelset.
> 
> Note: SEND_SIG_NOINFO matches the fact that SIGKILL doesn't have any info.
> 
> Reviewed-by: Christian Brauner <christian@...uner.io>
> Reviewed-by: Oleg Nesterov <oleg@...hat.com>
> Cc: <stable@...r.kernel.org>
> Fixes: cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")

Thanks for the patience! I think this is now ready to be picked up. :)

Christian

> 
> Signed-off-by: Zhenliang Wei <weizhenliang@...wei.com>
> ---
>  kernel/signal.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 227ba170298e..429f5663edd9 100644
> --- 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(SIGKILL, SEND_SIG_NOINFO,
> +				&sighand->action[SIGKILL - 1]);
>  		recalc_sigpending();
>  		goto fatal;
>  	}
> -- 
> 2.14.1.windows.1
> 
>