[PATCH v2] signal: trace_signal_deliver when signal_group_exit

[PATCH v2] signal: trace_signal_deliver when signal_group_exit

[Zhenliang Wei]

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@huawei.com>
---
 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

Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

[Christian Brauner]

On Mon, Apr 22, 2019 at 8:57 AM Zhenliang Wei <weizhenliang@huawei.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@huawei.com>

Just a nit below otherwise

Acked-by: Christian Brauner <christian@brauner.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
>
>

Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

[Oleg Nesterov]

On 04/22, Zhenliang Wei wrote:
>
> --- 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;
>  	}

Reviewed-by: Oleg Nesterov <oleg@redhat.com>

Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

[weizhenliang]

On Mon, Apr 22, 2019 at 6:37 PM Christian Brauner <mailto:christian@brauner.io> wrote:
>On Mon, Apr 22, 2019 at 8:57 AM Zhenliang Wei <weizhenliang@huawei.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@huawei.com>
>
>Just a nit below otherwise
>
>Acked-by: Christian Brauner <christian@brauner.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.