linux-kernel - [PATCH AUTOSEL for 4.9 26/52] workqueue: trigger WARN if queue_delayed

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Date:   Wed, 29 Nov 2017 17:21:19 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Tejun Heo <tj@...nel.org>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 26/52] workqueue: trigger WARN if
 queue_delayed_work() is called with NULL @wq

From: Tejun Heo <tj@...nel.org>

[ Upstream commit 637fdbae60d6cb9f6e963c1079d7e0445c86ff7d ]

If queue_delayed_work() gets called with NULL @wq, the kernel will
oops asynchronuosly on timer expiration which isn't too helpful in
tracking down the offender.  This actually happened with smc.

__queue_delayed_work() already does several input sanity checks
synchronously.  Add NULL @wq check.

Reported-by: Dave Jones <davej@...emonkey.org.uk>
Link: http://lkml.kernel.org/r/20170227171439.jshx3qplflyrgcv7@codemonkey.org.uk
Signed-off-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 kernel/workqueue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 296dcca77f33..181c2ad0cb54 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1506,6 +1506,7 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 	struct timer_list *timer = &dwork->timer;
 	struct work_struct *work = &dwork->work;
 
+	WARN_ON_ONCE(!wq);
 	WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
 		     timer->data != (unsigned long)dwork);
 	WARN_ON_ONCE(timer_pending(timer));
-- 
2.11.0