2019-04-22 06:59:31

by weizhenliang

Subject: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

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 <[email protected]>
---
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

2019-04-22 10:41:25

by Christian Brauner

Subject: Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

On Mon, Apr 22, 2019 at 8:57 AM Zhenliang Wei <[email protected]> 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 <[email protected]>

Just a nit below otherwise

Acked-by: Christian Brauner <[email protected]>

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
>
>

2019-04-22 15:34:36

by weizhenliang

Subject: Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

On Mon, Apr 22, 2019 at 6:37 PM Christian Brauner <mailto:[email protected]> wrote:
>On Mon, Apr 22, 2019 at 8:57 AM Zhenliang Wei <[email protected]> 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 <[email protected]>
>
>Just a nit below otherwise
>
>Acked-by: Christian Brauner <[email protected]>
>
>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.

2019-04-22 16:21:13

by Oleg Nesterov

Subject: Re: [PATCH v2] signal: trace_signal_deliver when signal_group_exit

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 <[email protected]>