linux-kernel - [PATCH 3.12 038/142] futex: Add missing error handling to FUTEX_REQUEUE

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Message-Id: <fca5410bf57b05c46a37fdf7d958e3bf9e563384.1491838390.git.jslaby@suse.cz>
Date:   Mon, 10 Apr 2017 17:31:59 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>, juri.lelli@....com,
        bigeasy@...utronix.de, xlpang@...hat.com, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jdesfossez@...icios.com,
        dvhart@...radead.org, bristot@...hat.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 038/142] futex: Add missing error handling to FUTEX_REQUEUE_PI

From: Peter Zijlstra <peterz@...radead.org>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 9bbb25afeb182502ca4f2c4f3f88af0681b34cae upstream.

Thomas spotted that fixup_pi_state_owner() can return errors and we
fail to unlock the rt_mutex in that case.

Reported-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Darren Hart <dvhart@...ux.intel.com>
Cc: juri.lelli@....com
Cc: bigeasy@...utronix.de
Cc: xlpang@...hat.com
Cc: rostedt@...dmis.org
Cc: mathieu.desnoyers@...icios.com
Cc: jdesfossez@...icios.com
Cc: dvhart@...radead.org
Cc: bristot@...hat.com
Link: http://lkml.kernel.org/r/20170304093558.867401760@infradead.org
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 kernel/futex.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index 9667d9233289..566e2e0e56cf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2496,6 +2496,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 		if (q.pi_state && (q.pi_state->owner != current)) {
 			spin_lock(q.lock_ptr);
 			ret = fixup_pi_state_owner(uaddr2, &q, current);
+			if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current)
+				rt_mutex_unlock(&q.pi_state->pi_mutex);
 			/*
 			 * Drop the reference to the pi state which
 			 * the requeue_pi() code acquired for us.
-- 
2.12.2