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

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Date:   Mon, 22 Apr 2019 14:56:05 +0000
From:   weizhenliang <weizhenliang@...wei.com>
To:     Christian Brauner <christian@...uner.io>
CC:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Oleg Nesterov <oleg@...hat.com>,
        "colona@...sta.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" <stable@...r.kernel.org>
Subject: Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

On Mon, Apr 22, 2019 at 6:37 PM Christian Brauner <mailto:christian@...uner.io> wrote:
>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
>>
>>

Thanks for your comments, I will adjust the commit msg and resend the patch according to your suggestions.
If there are other suggestions, please let me know. Thanks again~

Zhenliang Wei.