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From: Jamie Iles <jamie.iles@oracle.com>
To: linux-kernel@vger.kernel.org, oleg@redhat.com
Cc: Jamie Iles <jamie.iles@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH] signal: don't remove SIGNAL_UNKILLABLE for traced tasks.
Date: Thu,  4 May 2017 13:51:36 +0100	[thread overview]
Message-ID: <20170504125136.11352-1-jamie.iles@oracle.com> (raw)

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 <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jamie Iles <jamie.iles@oracle.com>
---
 kernel/signal.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 7e59ebc2c25e..5516a0cda668 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1185,7 +1185,11 @@ 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);
-- 
2.12.0.rc0

             reply	other threads:[~2017-05-04 12:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-04 12:51 Jamie Iles [this message]
2017-05-05 16:26 ` [PATCH] signal: don't remove SIGNAL_UNKILLABLE for traced tasks Oleg Nesterov
2017-05-05 16:34   ` Jamie Iles
2017-06-08 10:07   ` Jamie Iles
2017-08-15 11:28 Jamie Iles
2017-08-15 16:16 ` Oleg Nesterov

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