Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752147AbdHOL2V (ORCPT ); Tue, 15 Aug 2017 07:28:21 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:50162 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751843AbdHOL2U (ORCPT ); Tue, 15 Aug 2017 07:28:20 -0400 From: Jamie Iles To: linux-kernel@vger.kernel.org, oleg@redhat.com Cc: Jamie Iles , Andrew Morton Subject: [PATCH] signal: don't remove SIGNAL_UNKILLABLE for traced tasks. Date: Tue, 15 Aug 2017 12:28:06 +0100 Message-Id: <20170815112806.10728-1-jamie.iles@oracle.com> X-Mailer: git-send-email 2.13.3 X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1356 Lines: 35 When forcing a signal, SIGNAL_UNKILLABLE is removed to prevent recursive faults, but this is undesirable when tracing. For example, debugging an init process (whether global or namespace), hitting a breakpoint and SIGTRAP will force SIGTRAP and then remove SIGNAL_UNKILLABLE. Everything continues fine, but then once debugging has finished, the init process is left killable which is unlikely what the user expects, resulting in either an accidentally killed init or an init that stops reaping zombies. Cc: Andrew Morton Cc: Oleg Nesterov Signed-off-by: Jamie Iles --- kernel/signal.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/signal.c b/kernel/signal.c index 7e33f8c583e6..ed804a470dcd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1194,7 +1194,11 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) recalc_sigpending_and_wake(t); } } - if (action->sa.sa_handler == SIG_DFL) + /* + * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect + * debugging to leave init killable. + */ + if (action->sa.sa_handler == SIG_DFL && !t->ptrace) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); -- 2.13.3