linux-kernel - Re: [PATCH 05/17] signal: Bring down all threads when handling a non-coredump fatal signal

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Date: Tue, 25 Jun 2024 14:56:38 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/17] signal: Bring down all threads when handling a
 non-coredump fatal signal

On 06/18, Eric W. Biederman wrote:
>
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2882,7 +2882,13 @@ bool get_signal(struct ksignal *ksig)
>  		 * Anything else is fatal, maybe with a core dump.
>  		 */
>  		exit_code = signr;
> -		group_exit_needed = true;
> +		if (sig_kernel_coredump(signr))
> +			group_exit_needed = true;

OK... do_coredump() can fail before coredump_wait() even if CONFIG_COREDUMP

> +		else {
> +			signal->group_exit_code = exit_code;
> +			signal->flags = SIGNAL_GROUP_EXIT;
> +			zap_other_threads(current);
> +		}

dequeue_signal() and/or ptrace_signal() can drop siglock, I think
the else branch should re-check SIGNAL_GROUP_EXIT/group_exec_task.

Oleg.