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

BugLink: http://bugs.launchpad.net/bugs/1745047
[ 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>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 95cc76785a12187077e59ea24c8adfdbf4db6df9..85555eb4d3cb5a2fcafa55d234537aa1515d8cf9 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1479,6 +1479,7 @@ 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));