Patch "workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     workqueue-trigger-warn-if-queue_delayed_work-is-called-with-null-wq.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Dec 12 13:38:50 CET 2017
From: Tejun Heo <tj@kernel.org>
Date: Mon, 6 Mar 2017 15:33:42 -0500
Subject: workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq

From: Tejun Heo <tj@kernel.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@codemonkey.org.uk>
Link: http://lkml.kernel.org/r/20170227171439.jshx3qplflyrgcv7@codemonkey.org.uk
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/workqueue.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1479,6 +1479,7 @@ static void __queue_delayed_work(int cpu
 	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));


Patches currently in stable-queue which might be from tj@kernel.org are

queue-4.4/libata-drop-warn-from-protocol-error-in-ata_sff_qc_issue.patch
queue-4.4/workqueue-trigger-warn-if-queue_delayed_work-is-called-with-null-wq.patch