linux-kernel - [PATCH RESEND2 09/11] signals: disallow_signal() should flush the potentially pending signal

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Message-ID: <20140415183709.GA13433@redhat.com>
Date:	Tue, 15 Apr 2014 20:37:09 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	David Woodhouse <dwmw2@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Ingo Molnar <mingo@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Richard Weinberger <richard@....at>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH RESEND2 09/11] signals: disallow_signal() should flush the
	potentially pending signal

disallow_signal() simply sets SIG_IGN, this is not enough and
recalc_sigpending() is simply pointless because in can never
change the state of TIF_SIGPENDING.

If we ignore a signal, we also need to do flush_sigqueue_mask() for
the case when this signal is pending, this way recalc_sigpending()
can actually clear TIF_SIGPENDING and we do not "leak" the allocated
siginfo's.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/signal.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 3eec27b..4bab1b7 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3084,8 +3084,15 @@ EXPORT_SYMBOL(allow_signal);
 
 void disallow_signal(int sig)
 {
+	sigset_t mask;
+
+	sigemptyset(&mask);
+	sigaddset(&mask, sig);
+
 	spin_lock_irq(&current->sighand->siglock);
 	current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
+	flush_sigqueue_mask(&mask, &current->signal->shared_pending);
+	flush_sigqueue_mask(&mask, &current->pending);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-- 
1.5.5.1

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