linux-kernel - Re: [PATCH v2] signal: trace_signal_deliver when signal_group

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Date:   Mon, 22 Apr 2019 12:37:05 +0200
From:   Christian Brauner <christian@...uner.io>
To:     Zhenliang Wei <weizhenliang@...wei.com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Oleg Nesterov <oleg@...hat.com>, colona@...sta.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

On Mon, Apr 22, 2019 at 8:57 AM Zhenliang Wei <weizhenliang@...wei.com> wrote:
>
> In the following 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.
>
> commit cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")
>
> Therefore, we need to add trace_signal_deliver before "goto fatal"
> after executing sigdelset.
>
> Note: The action[SIGKILL] must be SIG_DFL, and SEND_SIG_NOINFO matches
> the fact that SIGKILL doesn't have any info.
>
> Signed-off-by: Zhenliang Wei <weizhenliang@...wei.com>

Just a nit below otherwise

Acked-by: Christian Brauner <christian@...uner.io>

You should probably make the line:
commit cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")
a Fixes-line right above your commit:
Fixes cf43a757fd4944 ("signal: Restore the stop PTRACE_EVENT_EXIT")

> ---
>  kernel/signal.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 227ba170298e..0f69ada376ef 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2441,6 +2441,7 @@ 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, SIG_DFL);
>                 recalc_sigpending();
>                 goto fatal;
>         }
> --
> 2.14.1.windows.1
>
>